Okay, a bunch of technology bloggers have covered this, but flickrvision is the coolest thing I've seen for wasting time in quite a while.
What is it? It's a slideshow of recent Flickr photos, but the draw is that the slideshow uses the world map on the background and shows you where each photo was taken. It has a flat map view (default), and a 3D view that spins a globe to show you where the photo was taken. Neato.