I came across a (free!) add-in a while back that provides integration of TFS Work Items with Microsoft Outlook 2003. This add-in provides the following features:
If you have business owners, testers, quality assurance users, etc. that would like to be able to create and/or manage work items within TFS without having to install Team Explorer (or some other 3rd party interface) then check out this add-in. It's definitely worth a look.
The current version supports only Microsoft Outlook 2003 but a version for Microsoft Office Outlook 2007 is in the works and planned to be released soon.