The Windows key between the Ctrl and Alt keys on your keyboard can do more than bring up the Start menu, try these shortcuts:

Windows Key + D: Show Desktop
Windows Key + E: Windows Explorer
Windows Key + F: Find Files or Folders…
Windows Key + M: Minimize All Windows
Windows Key + Shift+M: Undo Minimize All
Windows Key + R: Run…
Windows Key + Tab: Select Task
Windows Key + Break: System Properties
Windows Key + F1: Windows Help

You can also create your own shortcuts with the free Winkey software from Copernic.
Click to download
I use C for calculator and N for notepad, among others.