Over at Mozillazine, we came up with a pretty good way of creating CSS floats. I imagine someone else has done this, but I've never seen it. It works in Gecko browsers, IE5, IE5.5, IE6 and Opera 7.23 so far. It's also very simple, and the single hack which we employed is very easy to understand.
Here it is in action. Let me know if you find any bugs or a use for it.