I vaguely recollect it saying somewhere in the rules that Dive does double damage. A flying creature that charges down can do double damage. But I can't find the rule, so I'm wondering if that rule is still in 3.5.
Actually, I did look there. But the fact the fact that there's separate listings for "Flight" and "Movement Modes: Fly" gummed it up. Thanks again, 3.5!