I've just release the UKVSTS work item control library to CodePlex. The idea is to extend the work item user interface with some extra controls than shipped with Team System. So far the library contains two controls:

The library comes as an MSI file and will install all the pieces you need onto your client machine.

Screen Shot Control
This control provides a button that when clicked attaches an image that is currently in the clipboard. Before the image is attached, you will be able to crop and mark up the screen shot using the Image Editor.
For more details, please see Screen Shot Control
Check Box Control

This is a simple control that allows you to use a checkbox where you would normally see a drop down list box containing two items - basically it saves you a mouse click :-)
For more details, please see Check Box Control

More update to follow as I develop some more controls.

Neil.