It's even worse if you're running Linux on the MacBook. You have to fiddle with a mysteriously named keyboard preference ("Key to choose 3rd level") to get even the Alt+3 combination to work - and once it does, you can no longer Alt+Tab to switch between windows. Fortunately you can choose a different key; the best compromise I've found so far is to the right Alt key. That way you can enter '#' symbols and Alt+Tab back and forth, but it turns what should be a single keystroke into a two handed combination.
That and the lagging OpenGL support are why my next computer won't be a Mac.