Explorify is a Spotify client for the iPad, made by me @nevyn, and @mandy. However, it's not even demoably done :(

It was imagined to become a visual music exploration app, where you could add artists, albums, tracks, friends or playlists to an infinite canvas. Tapping an entry would ask last.fm and/or echo nest for similar music, which would be appended to the original music node in a graph-like structure. Making a slicing gesture would prune the graph of bad music. Pressing play on a node would start a random walk playing the graph.

I really tried to make a version of libspotify for mac os that could be released to the contenders here at MHD; however, after five hours of soul-shattering defeat after defeat I gave up. At least something came of it, though: me, mandy and @rsms made a cocoa wrapper around libspotify/openspotify if anyone wants it: http://github.com/rsms/spotifycocoa/ . We've extended the last.fm cocoa wrapper as well, ask us if you want it. Hopefully I can release the libspotify for macos later on as well.