Have you seen the Google Maps! The UI is really cool. Left click, hold and drag the mouse, the map actually moves! Google keeps obliterating the assumption that the web is not about just HTML, dynamism is the in-thing.
I am really surprised that others have not done such Web UIs before. Or maybe I've missed something.
Update : Just got to know there is a Google India Code Jam 2005 competition. The first prize is 3 lakh rupees! Wow.
Update : Simon Willison explores how Google Maps is working.