The Raskin Center for Humane Interfaces has released an alpha build of their new ZUI (Zooming User Interface) called Archy. Here is a screenshot of it in action:

If you're even peripherally involved in UI design, I strongly advise you have a read of the principles behind Archy, download it, and have a play with it.

I'm certainly having a long hard think about how many contempoary UI practices are optimal (especially given modern hardware) and how many we've simply inherited from older systems because we haven't given the matter any thought.