One of the most interesting applications for Windows Phone 7 I have seen so far is the Meteor Media Center application. Meteor is an advanced remote control for Windows Phone 7 and integrates really well in to Media Center. The UI is fantastic example of Windows Phone 7 development and is a really rich applicationt.
Checkout the videos bellow for a proper idea, I think this app and ByRemote will make Windows Phone 7 the best platform for Media Center users going forward. The developer’s web site also has lots more details on the features of the application
I’d love to run this app on our Lenovo S10 3T multitouch convertible and not just on Windows Phone 7.