Number 1:  moretrackstrackslikethis.com

A useful mashup of lastfm’s “similar tracks” service and Spotify gives a great way to find new artists and music matching your tastes.  What’s particularly good is that you can match single tracks, so even if you only like one track by a certain artist, you can find good matches.

Written in 100% Pure CSS3, HTML5 and JavaScript.

Number 2: admission that this is just shameless link-bait

There’s some other great mashups out there. Check Spotify’s list.