This neat application pulls down your Flickr photos and displays them very nicely within Media Center.  I've been playing around with version 1 recently which was originally written in Windows Presentation Foundation (WPF) and deployed as an XBAP but V2 has now been updated to leverage the Media Center Markup Language (MCML) which lets them use a lot of the built in look and feel stuff rather than reinventing the user experience wheel.

 

I like this concept (called Geocoding) which allows you to search by a location and see all related photographs - neat. Ian has a cool writeup of the new version here and to see the soapbox video demo check out the Big Screen official blog.