I think that Joudi posted the shortcut keys in his Tips and Tweaks section before but these are some others again :
Windows+Tab
Cycle through open applications on the task bar
Windows+Break
Open the system properties panel
Windows+F1
Start Windows Help
Windows+E
Open an instance of Windows Explorer, centered on "My Computer"
Windows+F
Open the "Find Files or Folders" dialog box
Windows+Ctrl+F
Open the "Find Computer" dialog box
Windows+M
Minimize all open windows
Windows+Shift+M
Undo the "minimize all" function (re-open all current windows)
Windows+R
Open the "Run" dialog box
I find the last one useful too for doing CMD or MSCONFIG