The TFS team continues to do a great job releasing Power Tools on a regular basis to the community even though they're also hard at work with TFS 2008 and Rosario.  Bryan and Brian have announced the details but at a high level the newest areas of focus have been work item templates (defining default values for common types of work item entries) and the Best Practice Analyzer (helps diagnose configuration related issues with TFS).  If these strike your fancy, don't hesitate to check them out.