Microsoft, Spotify, The Echo Nest team up on MixShape

Application plays virtual deejay, creating the ultimate playlist and visual display based on the user's mood.

A look at MixShape.

A triumvirate of companies have come together to deliver a new way of handling playlists, both in the browser and through Spotify.
Microsoft, Spotify, and a "music intelligence" start-up named The Echo Nest announced yesterday the launch of a visual playlist tool called MixShape. The feature allows users to toss their Spotify playlists of up to 300 tracks into MixShape and come away with a finely tuned playlist, complete with visual display. MixShape analyzes the tracks and creates a mix for the "optimal flow between songs." That flow depends on the "mood" the user selects, which, at this time, is limited to romance, party, work, or exercise.

Microsoft's presence in the deal means MixShape was designed to work with touch-enabled devices running Windows 8. The feature works across other operating systems and browsers, but the experience isn't as visually impressive.
I tried MixShape out on my Mac running Chrome. The feature works as advertised and you can maneuver your mouse around the page to pick songs and modify the "mood." MixShape also lets users export their playlists to Spotify.
MixShape officially launched in the U.K. today. It's still accessible, however, where Spotify is available.