I think, in my time here (slightly over a year), I've only ever seen one "real" ban. That was a guy named Thomas Young, who (aside from being a constant nuisance and speaking in the 'high and mighty' terms about spiritual evidence that only he had, but never giving it, and things like that) said a whole lot of sexist things, and then eventually directed them personally at one of the girls here, fernando_the_weasel at the time.
The only other sort-of ban that I can think of was facetiouspersona. He, of course, came back after a few days.
Before face, aside from thomas, I don't think our mods even did so much as warn anyone, much less do any real banning. So I think the list of bans are thomas young, then xii/metteyya/alice, and the only temporary ban goes to face