CMake - CMake is an open-source, cross-platform family of tools designed to build, test and package software.
Undrtone - Social layer on top of Spotify and Rdio from Scott Vener
SCons - SCons is an Open Source software construction tool—that is, a next-generation build tool.
PlaylistMap - Connect with Spotify playlist curators from around the world
Ninja Build - Ninja is a small build system with a focus on speed.
BeatSense - Discover great music hand-picked by real people, in a single click. FREE and in real-time!