Page Down = 'fn' + 'Down Arrow'
Page Up = 'fn' + 'Up Arrow'
Delete = 'fn' + 'delete'
Backspace = 'delete'
F1, F2, F3, .... = 'fn' + top row buttons OR
F1, F2, F3, .... = 'fn' + keys on control strip (Mac Book Pros with control strip)
Other cool shortcuts
To make screenshot of the whole screen: 'shift' + 'command' + '3'
To make screenshot of a portion of the screen: 'shift' + 'command' + '4' (crosshair would appear, press and drag the mouse over the potion you make to make a screenshot)
To make screenshot of an active window: 'shift' + 'command' + '4', then press spacebar, click on any window
All above would result in a PNG (Portable Network Graphics) file on the desktop.