Her are my Codeplex projects or those I participate to:

Community TFS Build Extensions
A library of TeamBuild 2010 activities.

WorkItem Query Administration
Work Item Query Administration (wiqadmin) is command-line utility to manage work item queries in Team Foundation Server 2008 and 2010.

UpdateAssemblyInfo Activity for TeamBuild 2010
Warning: this project’s content is now part of the Community TFS Build Extensions project.

The UpdateAssemblyInfo activity provides a way to manipulate the AssemblyVersion and AssemblyFileVersion attributes in AssemblyInfo files at build time. It works with C# and VB AssemblyInfo files.