Conchango, the creators of the Scrum process template, recently released a new tool for visualizing and managing work items in Team Foundation Server. With the Task Board for Team System it is possible to manage work items outside of the Team System tools using a stand-alone Windows application. The tool is currently in beta (beta 2 is due to be released on august 15) and requires TFS 2008 and v2 of the Conchange process template. The setup was a no-brainer and the tool is intuitive to use. Here's a taste of what it looks like:
Another option if you want this kind of tool but rather have it as a web application is to use the Scrum Dashboard, which is community tool you can get from Codeplex. Great add-on which is also based on the Conchango Scrum template.