Mitch Denny has been hard at work publishing the source to a bunch of TFS add-ons he's been working on.  Read about them on his blog links below and us know how useful they are to you...

TFS File Sharer - Mimics SourceSafe like file sharing.

TFS Continuous Integrator - A TFS 2005 based continuous integration solution.  Of course, it's built in if you are using TFS 2008.

TFS Dependency replicator - A tool to make changes in the source tree when certain events occur (like copying files when a build completes).

TFS Build Virtualizer - Rather than having one physical machine for each team or build server configuration, manage a pool of virtual machines automatically.