I just made a VGMdb style for the Last.fm "My Recent Tracks" image chart. If you wanna use it here in your sig, wrap this image in [img] tags:
Code:
http://imagegen.last.fm/vgmdb123/recenttracks/[#]/[your_username].gif
Change [#] to the number of tracks you want displayed (1-10) and obviously put your Last.fm username where [your_username] is. If you wanna play around with it some more, go
here.
-Mike