A tray icon to control basic Rhythmbox features. Requires Rhythmbox 2.9+.
You can rate the track, play/pause, go previous, go next, or quit.
Scroll up and down over the tray icon to adjust Rhythmbox's volume.
Click on the tray icon to show or hide the Rhythmbox window.
The tray icon has a green 'play' overlay when a track is playing.
When you hover over the icon, it shows the playing track.