Ear Geier does good work, particularly on all things creepy.
Too much underboob in the middle of a fight breaks my sense of realism/verisimilitude....but hell, Under Dust is a great game so I guess underboob is one of her mutant powers or something.
I dunno - Gamma World had some decently insane art too - and - Holy Buckets! - Erol Otis too! http://www.coldmonkeymountain.com/osrpg/gw_otus/otus5_opt.jpg
Eric is focused on the mutant thing ass shots, not the underboob.
For some really outrageous art look no further than Will Mcausland's Mutant Epoch whuch is the greatest non-clone retro post-apoc romp out there.