Twittersphere is a meme tracker for Twitter topics

Twittersphere is a new memetracker that tracks popular items being discussed on Twitter.

The service comes from Thomas Marban, the creator of the excellent popurls. Thomas says in a post:

there are several memetrackers for popular twitter stories but i've found most of them either too feature-rich or extremely inaccurate to include them on popurls. therefore, i've rolled my own at the melodic domain which is already fully-integrated into popurls, now powering the twitter block at the bottom section of the page. there are still a few quirks (mostly spam) to iron out, but you get the idea.
It's very simplistic, but that's the joy of it. Recommended if you want to know what's hot on Twitter.

(via Steve Rubel on FriendFeed)