The other day I was in a customer call and I was asked for a list of TFS External tools, I am defining those as any TFS feature or tool that is not included in the packaged product. Although I still don't have a compiled list the best advice I could think of was to give links to the places where this information is available. Here are those links and a bit of information about them:
1. TFS Development Center (http://msdn2.microsoft.com/en-us/tfs2008/default.aspx)
This is the main Team Foundation Server site and hence it provides a lot of information about our product, current news and released external tools. You can check out the CodePlex and Downloads sections for the latest releases (e.g. TFS MSSCCI Provider)
2. TFS Power Tools (http://msdn2.microsoft.com/en-us/tfs2008/bb980963.aspx)
Our Team Foundation Server Power Tools are a set of enhancements, tools and command-line utilities that improve the Team Foundation Server user experience. We try to release a new version every three to four months in order to keep with the growing customer demand
3. CodePlex (http://www.codeplex.com/Project/ProjectDirectory.aspx?ProjectSearchText=TFS)
In here just run a query with the keyword TFS or VSTS and you will get a significant number of tools developed by our community.
4. Third Party Tools
Attrice SideKicks (http://www.attrice.info/cm/tfs/index.htm) :Team Foundation Sidekicks is a suite of tools for Microsoft Team Foundation Server administrators and advanced users providing Graphic User Interface for administrative and advanced version control tasks in multi-user TFS environments.
TeamPrise (http://www.teamprise.com/): Teamprise offers a suite of client applications for accessing Team Foundation Server from outside the Visual Studio IDE.
Team System Rocks (http://teamsystemrocks.com/): Community site maintained by some of our MVP's focusing on news and tools. Their files tab contains a list of available tools that customers can utilize.
Personify Design (http://www.personifydesign.com/products/default.aspx): A Team System Partner with two products: TeamLook and TeamSpec
If you know of more links which I have not included here please let me know and I will add them.