I read about TiltViewer, a sexy photo viewer on del.icio.us. It displays Flickr photos, sorted by interestingness, in a three-dimensional black void that you can manipulate. The folks at Airtight Interactive built this bit of webby fun, and have a good attitude about it:
Does a 3D UI give more functionality than the equivalent 2D interface? No, but its certainly a lot cooler! Part of the motivation to build this was to explore ways to make 3D interfaces simple and intuitive.
Make sure you read about the controls. They’re not super intuitive (we don’t necessarily expect to use the keyboard)–the app could do with a little ‘?’ icon that users could click for pop-up instructions.