Like Windows, Ubuntu (and pretty much every other Linux) has a "Show Desktop" icon on it's toolbar that minimizes all the running applications to the taskbar allowing full view of the desktop.
I discovered it last week by accident whilst I was attempting to pull off a difficult triple-press-perfect-timing-required IDE 'shortcut' ;)
The keyboard shortcut for "Show Desktop" is:
Ctrl-Alt-DI also found a great linux desktop hotkeys article written by the Calgary Linux Users Group.
Technorati Tags: Show Desktop, Ubuntu, Linux, CLUG, Andrew Beacock