TeamCompanion is an Outlook plugin that integrates all your TFS work management in one place. It makes your TFS work item queries, reports, documents, etc show up in the Outlook content bar just like your mail, calendar, tasks, etc. It's VERY well done and very seamless.
Manage hierarchical work items. Monitor your projects using the project dashboard. Create Excel reports on selected work items. Access the work items in offline mode. You can do all of this within Outlook. With TeamCompanion you can take advantage of some standard Outlook features, such as the instant search feature which searches through all work item fields, even if you're offline, or the grouping and favorite folders features.
This screen shot of TeamCompanion demonstrates several things: 1) a Team Explorer like tree on the lower left for navigating your TFS content, 2) a hierarchical work item query with cool grouping ability to easily organize the results (here by State and Assigned to), 3) the preview form of the selected work item that is fully editable in place and 4) all the operations you can do on work items in Outlook (even including generating reports in Excel like you can from Team Explorer).
More Info: TeamCompanion