Playdar - music content resolver service
playdar.org
playdar.org
This is from Last.fm developers, esp. RJ (Richard Jones), mxcl (Max Howell; the guy behind Homebrew) and others.
The current source is written in Erlang. https://github.com/RJ/playdar-core
There is some old abandoned source written in C++: https://github.com/RJ/playdar
I found this while searching for the Boffin source code. Something about Boffin:
* http://blog.last.fm/2009/03/11/introducing-boffin-lastfms-mu...
* http://www.last.fm/group/Audioscrobbler+Beta/forum/30705/_/5...
And in the abandoned C++ repo, there is something about Boffin (haven't really looked much into it yet): https://github.com/RJ/playdar/tree/master/resolvers/boffin