Synergy is a tiny Cocoa application for Mac OS X 10.2 (and later) that puts three buttons to control iTunes in your menubar: previous track, next track, and play/pause. It also provides you with visual feedback about the currently playing tune and allows you to control iTunes via system-wide hot key combinations. These features provide a very fast way of skipping between songs when using the keyboard or the mouse, without having to switch to iTunes or access its Dock menu.
WinSwitch is a compact replacement for Apple's Fast User Switching menu on Mac OS X 10.3 that saves menu bar space by allowing you to show an icon, custom user picture, or short username instead of the full username, while faithfully replicating and improving the other features of Apple's menu.