On the Windows version of Photoshop, you can select the top menu by pressing Alt, and then have full navigation of the menu using only the keyboard. For example, Alt->I->A->C is the shortcut for Image -> Adjustments -> Brightness/Contrast. That's just one of many sequences possible. This system is what makes the Windows version the definitive Photoshop for me... so why isn't it on the Mac version? Pressing Alt on the Mac version does nothing.