For starters, there is the "munchkin" type titties for those in the A and AA class.  Good things come in small packages, eh wot?

Then there is a shape characteristic of gals from the Indian subcontinetnt which have a peculiar oval shape of there own which is quite fetching.

Then of course, the just plain huge ones which resemble watermelons

Champagne glass shipped boobs.  (Not champagne flute shaped obviously, but the shallow glasses.) It was said Marie Antoinette had champagne glass breasts that enchanted the lovers she had.