Saints row 2, and WWE games, pretty much, as others have said. I've no recllection of seeing a game do it better. The detail potential is really quite high.
Way of the Samurai series is worth mentioning, though for the accessory system alone. You can pick accessories, and place them on your character in pretty much what ever fashion you want, even if they're floating off, or clipping into your character. Adjusting XYZ axis, size, and such.
That's on top of the ability to pick heads, hair, bodies, clothes, swords (which an entirely diffirnet level of customization), and gender.