I've written a
GreaseMonkey script for
Last.fm (formally Audioscrobbler) that adds chart position change information to the weekly charts. My first release was last weekend but the html/css was quite broken so it didn't look right, also my graphics were rubbish. Fortunately a friendly Last.fm-er has fixed it and drawn some new graphics for me! While it might not be the biggest open source program in the world (it's only 190 lines of JavaScript) it's always nice to receive a fix for broken code.
If you're a Last.fm-er and use Firefox visit
here to download it.