Spotalike - Spotify playlist with similar songs, according to Last.fm
Bowtie - Bowtie is a desktop accessory that allows you to see and control your music (iTunes, Spotify...
MusaicFM - An iTunes like screen saver based on Spotify and Last.fm
Muzzy - it’s a tiny and gorgeous iTunes companion that lives on your menu bar. For Mac OSX, its free!
Owlead - Grow your Twitter with valuable followers, effortless
Magic Playlist - Get the playlist of your dreams based on a song