ReqSheet enables offline creation and editing of requirements.  The tool manages a simple, lightweight requirements hierarchy and can be synchronized with TFS.  The requirements "documents" can be emailed, shared via Sharepoint and more.  Along with their storyboarding product, Reqsheet creates a great solution for requirements elicitation with TFS.

Check out more at the stpSoft web site: http://www.stpsoft.co.uk/vsts/

Brian