As you might know, Noatun (with a Kaiman module) is the new KDE 2.1 multimedia player. Noatun supports plugins on a very deep level, and a rich API allows large amount of control of the entire
application. A new document is now available with developer information on writing playlists, user interfaces, visualizations, and even coffee-makers for Noatun. ;-) Also available, an API reference.