Gnome Music Player Client
Features and usability
GMPC is a front-end for Music Player Daemon and as such it just uses it's for music library index and controls it's playlist and playback. You need to have MPD configured and running to use GMPC.
GMPC has a very userfriendly and strait-forward interface. It has a "Now playing" view, your Play Queue, Album View and Database View where you can browse your music collection. Then there is a most powerful Search function where you can filter by artist, album, track, name, genre, date, composer, performer, filename and albumartist. You can do a search query on your music collection, your playlist and also external services like Magnatune and Jamendo.
GMPC is overall a really nice interface for the Music Player Daemon. However, it does lack some of the more advanced features the MPD front-end Cantata has such as dynamic playlists based on how you've rated songs and other factors. GMPC is fine if features like that aren't important to you.