Quakr is a project to build a 3-dimensional world from user contributed photos, a.k.a. some friends having fun with geek hacking. I see they submitted an abstract to XTech too. The blog links to some interesting experiments mashing up Google Maps with a Flash and VRML viewer.
The Quakr 7D Tiltometer is worth viewing too if only for its sheer Blue Peter stylee “build this at home” excellence.