I only use one: the two finger scroll. I started using it about a year before I owned any apple laptop (I think it was on a viao?) And it bugs the crap out of me that my lenovo doesn't use it.

The two-finger back-forth fills me with rage b/c of how often I have lost unsaved work on the Internet by accidentally going back one page. <sigh>

Then again, I do the same thing with [backspace] on my windows box sometimes.

I started with two finger scroll on my pc and two finger right click, but it was not the same.

I got a mac a few weeks ago and I've been discovering these gestures and loving them. Common ones I use:

two finger right click

four finger swap fullscreen apps (lion)

two finger scroll

two finger back/forward (not a very common use case)

three finger text select

three finger window drag

three finger window resize

I disabled pinch zoom, hate it. Same with rotation.