OurSignal [oursignal.com] looks at currently popular items on the top social news sites (i.e. Digg, Reddit, del.icio.us, Hacker News) and mashes it all together in an interactive treemap, very similar to the well-known Google NewsMap. The idea is to allow users to get a rapid overview of what the latest breaking headlines are at the frontline of the intermatubes.
The bigger the rectangle, the more relative votes a story has. The warmer the color, the quicker the story is on the rise. Cooler colors denote negative velocity. All sources are refreshed every 15 minutes.