It would be cool if you indexed the sites people are tracking (with their permission) or at least had an index showing changes on the top N sites on the web. I'

It would be cool if you indexed the sites people are tracking (with their permission) or at least had an index showing changes on the top N sites on the web. I'd like to be able to browse changes across Facebook, Google, etc., without having to set up a feed, add it to my reader, and wait--it'd be great if I could see a history right away.