(before I forget to answer)

*Those* tools! That was too easy. ;)

I have used all of them at least once, except for the Notes tool and the Slice tool.

My tool uage is pretty average, I guess. The ones I use most often are: the marquees/move/hand/zoom, then brush/airbrush/gradient, and then blur/stamp/dodge/burn/erase. I love using masks, is that a tool, too?

It's hard to stop here, I could list more. :) I try to work with keyboard shortcuts as often as possible, so I hardly notice how often I'm using the eyedropper, for example.