Linux only: Recent switchers from Windows to Linux are probably used to using the Windows key to open up the start menu — to get the same thing on Linux, you'll have to tweak a simple setting instead.
Over at the How-To Geek site (my home away from Lifehacker), we noticed that since Ubuntu 9.10, you can no longer assign the Windows key directly through the Keyboard Shortcuts dialog — if you want to set that key to open Gnome's main menu, you'll have to resort to the command line instead. To make the change for yourself, open up a terminal and paste in the following:
gconftool-2 --set /apps/metacity/global_keybindings/panel_main_menu --type string "Super_L"
Readers should note that assigning the Windows key will cause problems with other Windows key combination shortcut keys, and you could always learn to use the default Alt+F1 combination — but if you're still determined to use the Windows key instead, this is how you can do it.