The last one is a way of minimizing all windows, but there is an easier way: Most keyboards have the windows key (between alt and ctrl) and if you press and hold that, then press d, it will minimize all windows or "Show the desktop." If you press the combination again (windows + d) before you've opened/viewed any windows, it will bring up the windows again that you had up in the same order.
This shortcut works on XP as well as vista (and probably 2000 as well).
