Improved Flyby Attack( Savage Species, p. 36)
You can attack on the wing with increased mobility.
When flying, you can take a move action (including a dive) and another partial action at any point during the move. If this partial action is an attack, you incur no attacks of opportunity for moving through areas threatened by your target. You cannot take a second move action during a round when you make a flyby attack.
Without this feat, you can take a partial action either before or after your move. Even with the Flyby Attack feat, you incur attacks of opportunity for moving through areas threatened by the target of your flyby attack.