I learned this not from searching Google but from venturing into the Windows Store. There's a handy app titled Windows 8 Cheat Keys you can install for free. It contains the Windows + PageUp suggestion plus a whole list of other handy shortcut keys you may not have heard of, such as Windows + Plus (or Minus to zoom in and out, and Windows + B to display the current active desktop app.
The app also has other nice tidbits like how to hide notifications.