"Another project you might like is the Olin College Marauder's Map. Writeup here: http://www.olinprojects.com/the-marauders-map/ Paper is here: http://www.springerlink.com/content/b519q72254lkuj05/ (it's not freely available :-/). It's a Wifi localization system some friends of mine at Olin put together to automatically figure out what room you're in and then draw you on a big harry-potter style map webapp. I put together an Android client, and its very neat to be able to look and see where people are from my phone!"