Thankfully the OS X equivalent of the ‘system tray’ in the menu bar is only open to 3rd party applications in a very limited manner (running apps are able to place an icon and menu there) but relatively few do. The only permanent items are for system things like volume, wifi network, backup, sync and language.

It has always struck me as weird that the system tray is treated as yet another place for application’s to dump their icons, after already having littered the desktop, start menu and quick launch bars.