While looking for a good way to popup a folder when I hit a shortcut combo, I ran into this: Keyboard shortcuts for Windows. It's a simple list, but it's got a lot of things I never knew. The the fantastic "Windows+Break" to pull up the System Properties. This is a small thing, but it will be very helpful to remember.
It was, however, missing my two favorite shortcuts.
1. Ctrl+Shift+Esc: Pulls up the Task Manager, which doesn't automatically come up with Ctrl+Alt+Del on most machines inside a business.
2. Windows+L: Locks the system, so the password must be entered to use again, but doesn't close any programs. This is really useful in a business environment where you want to keep people out of your computer.
Call this my public service announcement. I know it's odd for me to mention Microsoft without it being in reference while talking a competitor, but I can't always be a hater.