1. Windows Logo + L
Locks the PC instantly.
2. Shift + Delete
Deletes and bypasses the Recycle Bin entirely.
3. Alt + F6
Quickly switch between multiple open windows within a given application.
4. Shift + CTRL + N
Create a new untitled folder from within explorer.
5. Windows + M
Minimize all open windows to the taskbar.
6. Windows + Spacebar
All of your open windows will turn transparent so you can see right through them until released.
7. Windows + Shift + Left or Right Arrow
Moves window from one display to another.
8. Windows + 1, 2, 3, etc.
Press Windows + 1 to launch the first pinned app in your Taskbar (from left to right). Windows + 2 launches the second one, Windows + 3 launches the third one, and so on.
9. Windows + T
Scroll through apps that are already open on the taskbar, and hit Enter to select the one you want.
10. Windows + (+/-)
Zoom in for a magnified view.
http://www.maximumpc.com/article/features/10_coolest_windows_shortcuts_you_never_knew_about
– Main.FredPettis - 2011-10-01