Good idea for a thread! I'll have to have a good think about it, but here's a few that will go on the list:

Fiat Multipla (one of the most truly stupid looking cars of all time)
Porsche Cayenne
BMW X5 (possibly)
Ford Ka (possibly)

I've never seen the Ssangyong Rodius before now, but having seen it it probably will go on my list. By the way concept cars shouldn't count, this list should only be for amazingly ugly cars that car makers actually had the gall to release to the public market. Renault and BMW have been big offenders on this front recently.

I agree with most of the choices on this page, except the Aston Martin Lagonda (I think it's a striking OTT (in the good way) fantasy car, a bit like the Lamborghini Countach and I like it the way some people like cheesy old horror and sci-fi films) and the AMC Pacer (Wayne's World made that car cool, though the particular version shown in the picture is a bit ugly). I guess one man's trash is another man's treasure.