Keira Knightley is pretty flat-chested, but hot (before she became anorexic). She made up for her lack of boobiture with a sweet, toned butt and amazing legs. Boobs are a hard way to judge a woman since you're either born with them or you're not, or you get implants (which I'm not a fan of).

In most cases, women have to work at it (run, exercise, stay active) in order to get a toned and sexy butt. That makes it all the more appealing, knowing your woman isn't an Oprah-watching coach potato.