There really are none, here are a few:
As a girl you cannot fight in the arena at the fort, as a guy you can
As a girl you can sleep with Benny and kill him in his sleep, as a guy you must fight him in the lobby or at the fort (if you have high enough speech I think you can fight him alone)
As a guy you can get free repairs from the guy at the Mojave outpost (Only if you have the required caps and only once)
Those are really it...