I'm always excited when this thread comes up, because the subject title is tremendously enticing, but I'm usually disappointed at what shows up. Usually saggy and slim, rarely gigantic. I think the only two girls that have been posted that actually qualify are Anya/Merilyn and Limor Blokman -- both wondrously well endowed.
Somebody who is eminently qualified that HASN'T been mentioned is Hitomi Tanaka. I think this picture of her is charming, although it doesn't show the truly outrageous proportions of her breasts, but I use Photobucket and they don't like it when I try to post nekkid stuff: