I recently had to put together a list of links to code samples. This isn't even close to comprehensive, but it should help you get going if you are looking for something.

Version Control

• How to Write a Team Foundation Version Control Add-in for Visual Studio
• Team Foundation Version Control client API example (RTM version)
• Displaying the sizes and dates of files in the server
• Displaying the labels on a file, including label comments
• Example usage of VersionControlServer.CreateLabel
• Compare the content changes in a shelveset with any checked-in version
• How to check in changes on behalf of other users
• Sample checkin policy: make sure the comment isn't empty
• How to validate check-in policies, evaluate check-in notes, and check for conflicts
• How to compare (diff) trees at different versions using the API
  • My take on this: http://blogs.msdn.com/buckh/archive/2006/04/06/project_diff.aspx
  • Robert Horvick’s approach: http://blogs.msdn.com/roberthorvick/archive/2006/04/07/571043.aspx
• Merge history
  • Discovering TFS merge history using the client API - Part 3 (Deletes and Renames)
  • Discovering TFS merge history using the client API - Part 2 (calling QueryMerges)
  • Discovering TFS merge history using the client API - Part 1
• Programmatically showing differences between files
• Code snippet: What are my effective permissions {globally, to an item}?
• Show all pending changes on the Team Foundation server older than a given age
• Scanning history for the changesets that had policy override - simple usage of QueryHistory
• Version Control RSS Feed

TFS

• How to get the login dialog when using the Team Foundation Server API
• Listing the process templates on a TFS server
• How to list the users/groups the server knows about
• Code snippet: How to convert an account (DOMAIN\user) to its friendly name
• Simple command-line example: listing the team projects on a server

Work Item Tracking

• Creating a TFS Work Item from an Outlook mail message using VSTO
• Potential powertoy: paste from clipboard into work items as attachments
• Getting associated changesets for work items
• Getting Changeset objects from associated work items