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.
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.