Spotalike - Spotify playlist with similar songs, according to Last.fm
Figure - Propellerhead creates world-class software products and services that inspire music makers and provide the foundation for a worldwide creative musical community.
MusaicFM - An iTunes like screen saver based on Spotify and Last.fm
SoundGrail - SoundGrail Music App designed for pianists, guitarists, and DJs.
Bowtie - Bowtie is a desktop accessory that allows you to see and control your music (iTunes, Spotify...
Splice - Music creation, collaboration, and sharing made simple.