Spotify does not officially support Linux at the moment. However, they have developed a preview build of Spotify for Linux, which works well. As its a preview release, this version is still unsupported. Read more hot
AlsaPlayer is a type of PCM player. It is heavily multi-threaded and tries to excercise the ALSA library and driver quite a bit. It has some very interesting features unique to Linux/Unix players. The goal is to create a fully pluggable framework for playback of all sorts of media with the focus on PCM audio data.