Window Switching Hotkey

Can there be an OS independent hotkey to focus window 1 or window 2...etc.

This would be handy, as I often don't know which window I have focused and alt+tab always just switches instead of goes do a definite one.

Furthermore.. maybe instead you could do hotkeys for each grid element.

so if I had it set up like this
 ______    _______
|A  |  B |    | C |   D|
|    |     |     |     |     |
|______|    |______|

It would be super cool if I had a configurable independent hotkey for each (ctrl alt a, ctrl alt b, ctrl alt c, ctrl alt d) or something.