I find digg labs very impressive as a set of visualisation tools for a fast-moving link sharing site. My own favourite is BigSpy. The wonderful Stamen Design are behind these tools, and just in case they weren't good enough before, I notice they now have Ben "Flickr" Cerveny and Tom "Travel Time Tube Map" Carden on staff. Wow!

This video of digg users swarming over the recent iPhone announcement is quite interesting.