Chris Sells is the Content Strategist for the Longhorn Developer Center web site on MSDN.
Browsing his site at http://www.sellsbrothers.com/ I found his tools page here: http://www.sellsbrothers.com/tools/. There are some interesting little apps to have a play with, for example the FormatDesigner makes it easy to see how format strings work with multiple data types and cultures, and the .NET IM Client Classes lets you manage an IM connection and IM session.
Enjoy