In doing research for my Zoomable Tree interface, I ran into a video of a talk that Aza Raskin, founder of Humanized, gave at google on his vision of where the user interface is going (I can't believe I watched the whole thing: all 1.5 hours). I actually saw this after I finished developing the Zoomable Tree experiment. It inspired me to look at/come up with some alternative user interfaces that I could use for LearnIt that would be very simple. So I'll be posting about my findings as I continue researching and experimenting.
You can mess around with a experimental flash Zooming User Interface (ZUI) on the Raskin Center Website. Its pretty interesting to mess around with but I think there are things that can be done to make it quicker to navigate.