Cycle between Windows:
I used to use the Alt + Tab keys to move between Windows Vista/XP/etc, but that doesn't work so well in Windows 7. If you linger on a Window for a second too long, you'll switch to that Window when all you want to do is continue to scan the Window before selecting. Awkward. So now I use Windows Key + Tab which is just OK, but better than Alt + Tab.
Minimize all Windows:
Windows Key + M
Focus cursor in the address box of browser:
CTRL + L