Dual homing missles
it would only be fireable from vehicles (or only flying ones, if possible) and it would home in on the closest player, so basically, the homing vector but with rockets and (if possible) actually avoidable.
Not automatic, and they have about the same-Plus-half the cooldown of the rocket launcher (or mini-nuke).
If you had ever played battlefeild vietnam, make it act like the homing missles equiped on the F-14 phantom.
Oh also, it'd be cool if you could make them corkscrew instead of go in a straight line.
