Windows 7 comes with lots and lots of keyboard shortcuts. Some of them being extraordinarily handy. Here are my favorites:
Open Command Window from Windows Explorer
In Windows Explorer, right click a file or folder while holding down the shift key. This will give you the “Open Command Window Here” command to open a Windows Command Window (“cmd”) pointing to the current location.
Maximize/Minimize/Dock Active Window
Using the Windows Key combined with the arrow keys you can execute the “maximize”, “minimize”, “dock left” and “dock right” commands from the keyboard.
Move Window to Second Screen (For desktop extended to 2 monitors)
[Win] + [Shift] + [Left] / [Win] + [Shift] + [Right]:
Look through all open windows
Using [Win]-[Space] lets you see through the open windows and look at your desktop.
Set Presentation Settings
[Win]-[P] lets you select the presentation settings (Computer, Projector, Extend, Clone)
Start Applications in Taskbar
Press [Win] +  to start the application on the first position on the left in the taskbar. The number corresponds to the position on the taskbar.
And some old ones I like very much:
[Win] + [Shift] + [N]: Create a new folder
[Win] + [E]: Open Windows Explorer
[Win] + [M]: Minimize all windows
[Win] + [R]: Open “run”