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Using Touchatag reader from C#?

I happen to have an old RFID reader from Touchatag. It's pretty old already but it seems to work fine. Unfortunately, Touchatag has stopped their support for this device and besides, it required an internet connection which doesn't make it a very practical solution...
What I would like to do is to use this device without the need for an internet connection and inside an application that's written in C#. Don't know what this app is going to do, but right now I'm investigating all the options that are available for this device. So, does anyone know a good C# library and other sources that allow me to use this device?
(Btw, this is purely experimental.)

I don't know of any C# libraries of hand, but you can check out either:
IOTOPE
Java project that includes a low level library and a more high-level interface to the reader. You can probably adapt it to provide an interface to your C# application.
See http://blog.iotope.com/node/quick-starter/
libnfc
Low level NFC library. Mostly targeted for unix like systems, but could be put to work on windows as well.
See https://code.google.com/p/libnfc/

If you're experimenting with RFID, rather than works the bugs out of interfacing with a custom reader, you can buy a cheap USB RFID reader for around 10 £/$/€
A lot of them simply act like a keyboard and 'type' characters into your application (some even add a carriage return which is handy)

Capture camera using DirectShow

I'm developping a SmartDevice application (Pocket PC 2003 template) in C# for a device with Windows Mobile 6.1. I need to use the camera of this device (photos, video); to do this work i tried using the CameraCaptureDialog class but it does not work for Pocket PC applications.
So, I documented on the internet and found that I probably refer to DirectShow API, but the problem is that I do not know where to start because I can't found a working/correct example.
My questions:
Is this the right way? Are there alternatives?
Where I can find a very good example that shows how to do this work?

You may try directshowbetcf: http://alexmogurenko.com/blog/directshownetcf/ if you really want to go with DirectShow and NetCF.

There's plenty of examples of directshow on the web. There is a site dedicated to converting the API over to C# which makes it a lot easier, maybe this was it http://directshownet.sourceforge.net/about.html. I struggled with DirectShow until I read the book "programming directshow" from microsoft press. About a third of that way through that book it all seemed incredibly easy and I was able to complete what I wanted. In the end it's a lot like referencing any library and using the classes from within that library. The added difficulty is that you need to add wrappers because they are all COM objects but that has been done for you.

This might be useful to you to understand the DirectShow technology. Basically gives a start to DirctShow and explains some of the important points. But its C++ not C#. Hope this help
Basic Video Capture

DirectShow is the video capture API in Windows Mobile 6. There is a Video Capture Filter there and all in all things are designed pretty much the same way they are in Windows.
The problem is that however that this is a native API, and not just in Windows Mobile. To develop in C# you need some bindings and they are missing. On desktop there is DirectShow.NET, which is a missing piece, but it does not seem to fit well for CE. Yet you still need to fill this gap in Windows Mobile.
To work it around you have a few ways, the first would be to go through DirectShow.NET and update it appropriately to start working on your device, strip parts missing in mobile OS etc. This would get you a twin for DS.NET but for mobile operating system.
Another option would be to do some C++ development and implement the minimal sufficient feature set in that domain, exposing the component via COM. Then you will reference this from managed code and things will get connected together. And another obvious option would be to use a third party solution which already does one of the mentioned above.

How to simulate keyboard input in ALL applications?

I'm writing an app (in C#) which as a part of it must simulate and send some key strokes to another application. I'm using http://inputsimulator.codeplex.com/ project for simulating keys, and it works in many applications, but in some it doesn't - i.e. Mortal Combat 4.
I've googled about it, and found many answers varying from 'it's impossible' to 'you must use XXX library' etc. Those answered scared me a lot, and even nearly convinced I'm not able to do it at that time, BUT...
M$ Virtual Keyboard works. It works in ALL applications. So it IS possible... Does anyone of you, clever guys, know how can I achieve this?

Ok, I think I finally got it to work. I used API Monitor recommended by Neal P and it showed just minimal differences between OSK calls and mine. A bit later I've tried to make my calling thread sleep some time between sending messages with press and release key and that was it.

Although you were able to achieve your purpose, the way you achieved it does not fundamentally answer your question: How to simulate keyboard input in ALL applications?
There's a bunch of situations where the common user mode Microsoft API already mentioned does not work, like game applications that use the DirectInput API or protected games.
I have built a library that can help in this situations, it provides a simple C API that internally communicates with device filter drivers. It is able to send input for DirectInput based games and also is able to bypass some game protections. I have checked and it is still able to bypass some known game protections by using the x64 version of the library. Game protections commonly hook only the x86 system's api. Well, at last now, 18 February 2012, this is what I'm seeing happening.

Take a look at SendKeys on MSDN

fingerprint reader software using C#

I am planning to verify the user input for my application using the biometric input. I did some research on net and came up with following options of biometric input:
Fingerprint
Facial Recognition
Retinal Scan
Iris Scan
Voice Recognition
Signature Verification
Out of which I felt the fingerprint as most suitable options. But the problem with this is the API of the fingerprint device will vary with its hardware. So most probably I think I will need to code against the multiple devices API, which I don't find friendly.
I intend to do the programming stuffs in C#. Is there any way out of this. As I am new to this I'm clueless. What is the way to attack this problem and how vast is the project scope and what should be my approach for this project.

The problem is not unique to fingerprint readers, it will apply to all other options in your list and many other peripherals. In fact a standard API is the exception.
So you will have to look for somebody selling a library for this or writing your own (COM and/or Interop). And rolling your own will usually not be small or simple project.
Your program will have a list of supported devices, excluding the rest.

A colleague of mine was tasked with building a biometric based staff clock-in system for the company we both worked for. We, IT, choose Fingerprints as the biometric source. He researched and used this library from Bayometric - Griaule Fingerprint SDK along with some cheap MS print readers. From what he showed me and talked about at the time, does lead me to believe that this .net library had a nice API and was easy to work with.
The biometric system is still being used today, some 5 years later.

I work in the biometric field, and I use C# for a lot of the fingerprint stuff I do. My company had to develop a fingerprint device abstraction library for this very reason. Consider that all fingerprint scanners only REALLY need one call: getImage. Knowing this, my company wrote a library which initializes and sets up each device, creates a generic wrapper, assigns a unique ID, and throws it into a big list that you can enumerate over.
Then from the C# side all you have to do is "pick" a device (all you have to go on is a unique ID and maybe a manufacturer) and then use it. The image data that comes back has to be decided on in advance so that you know what you're going to get every time
The main problem with this approach is that a lot of devices these days have various gimmicks (e.g. programmable flashing lights), and by abstracting the devices away you lost the ability to access these special abilities. Furthermore, some devices actually return multiple channels of data (various spectrums of light for example) and you have to throw away all but one channel so that the application can remain device agnostic, which is a hard decision.
Finally keep this in mind: if you do minutiae extraction, the device you use unfortunately WILL impact which minutiae are detected. Some devices are "tuned" for certain algorithms, and so enrolling with device A and matching with device B may not work at all despite having picture-perfect fingerprints.

There is a similar question here: finger print reader for .net windows forms / WPF or silverlight client
Check the links in the answers

Snapping pictures from Windows C# Canon SDK vs PTP or MTP

I am hoping to receive some general guidance on accomplishing a seemingly simple goal. I have a DSLR camera (Canon EOS 50D) and need to write an application that will tell the camera to take a picture. I also need to transfer the picture to the computer and possibly delete it from the camera's storage. A bonus would be to get a live preview from the camera in my application. My environment will be Windows (either XP Pro or Vista Enterprise) and .Net 3.5 (C#).
I have done some research and found a couple of options. One I know will work, but limits me to using only Canon cameras in the future. I have found and downloaded an SDK from Canon that provides a lot of this functionality. I've looked over the SDK and while it's extensive and written in C it does have C# wrappers that will speed up development a bit.
Another option I've found is called Windows Portable Devices. Apparently, it is an API that will talk to devices that implement PTP and MTP standards. It is COM based and as far as I can tell it has no .Net wrappers. This is not however a show stopper. I could P/Invoke the functionality I need or write a Managed C++ DLL to use in my application to talk to the camera.
I am looking for anyone with experience with WPD to give me pointers. I've perused the documentation and seen references to transferring images and deleting images. I have not, however, seen mention of commands to take a picture, get a preview image, or say focus/auto-focus.

The WPD api provides the command WPD_COMMAND_STILL_IMAGE_CAPTURE_INITIATE
I am not sure whether your camera supports it but it should be simple enough to find out. If you can get the "wpdinfo" tool from the driver development kit and start it with your camera connected then send it a WPD_COMMAND_CAPABILITIES_GET_SUPPORTED_COMMANDS command and see if it supports the still image capture command. IF so then you could give that a try.

The comment from TallGanglyGuy is incorrect. ptp does allow you to trigger new images and change exposure, etc. Some cameras have firmware that only exposes some of the ptp commands.
PTP supports common device controls, such as taking a picture, so that
the user could take advantage of the PC/camera combination in new and
different ways again, without requiring additional software.
quoted from http://msdn.microsoft.com/en-us/windows/hardware/gg463507.aspx#EXC

try my Eos Framework: https://github.com/esskar/Canon.Eos.Framework
IMHO it's a better alternative then the .cs file that comes with the SDK.

PTP and MTP are both protocols for transferring files from a digital still camera (DSC). The protocols provide no functionality for triggering new images, or setting exposure control. You will be stuck using the camera specific SDK. If you want multiple vendor support Nikon has an SDK that provides similar support as the Canon SDK for their cameras.
More info on PTP and MTP can be found here:
http://en.wikipedia.org/wiki/Picture_Transfer_Protocol
and
http://en.wikipedia.org/wiki/Media_Transfer_Protocol
EDIT
I forgot to mention that WIA may be interesting to you, assuming your camera's driver provides a WIA interface.

This is really generic, but it may help.
I had to write an application that used two different bar code scanners from two different vendors with different SDK's. I created an interface that defined the methods and events that I wanted to code for, and then wrote adapter classes that implemented my interface.
This worked well in my case, and switching from one to the other was pretty seamless. If you took the same approach, you wouldn't be totally dependent upon one SDK.