Two- or three-line horizontal menus

On the two sites I run, I've hacked together a multi-line cascading horizontal menu, with lots of crazy CSS goodness and (somewhat) graceful degredation to IE (no rollover popups, but workable click-and-next-line-updates functionality). Example is here: http://www.dasnet.org (works with Firefox, works moderately with Safari (some visual glitches), and doesn't rollover with IE).

I'm wondering if this might be possible with Nice Menu as well. It might even be as easy as updating the CSS, but I suspect there'd be some .js work to be done, too. I really prefer this approach, because it helps show where you are in the overall menu, even to three levels down.

I've not yet needed to go to a fourth level, but I've always figured that would be handled by the 3rd level rollovers simply popping up temporary vertical menus and you go from there, but don't see the final deeper choice reflected in the three main lines.

The biggest hurdle in implementing this is having the entire menu tree available at the browser, to be selectively displayed by the css/js code. I accomplished this by hacking up menu.inc, flagging leaf nodes as "leaf," intermediate nodes which were not active as "collapsed," and intermediate nodes which were active as "expanded". I can dig up my hack for an example, but it might be better if someone could independently create something not quite as klugey as mine. :)

Any thoughts?