Fleet of Foot from Complete Warrior: Would a Dragon be able to use the Fleet of Foot feat while flying? The feat states: "When running or charging..
A dragon or other creature that's flying can typically realize the benefit of the feat Fleet of Foot (Complete Warrior 99). The feat's benefit says
When running or charging, you can make a single direction change of 90 degrees or less. You can’t use this feat in medium or heavy armor, or if you’re carrying a medium or heavier load. If you are charging, you must move in a straight line for 10 feet (2 squares) after the turn to maintain the charge.
The Monster Manual on Movement Modes says, "A creature can use the run action while flying, provided it flies in a straight line" (312), and it says this in addition to adding a chargelike attack dive to a flying creature's ability to make normally the special attack charge (Player's Handbook 154–5). (The Rules of the Game Web column "All about Movement (Part Five)" describes possible changes to a flying creature's normal charge.) (Also, the contradictions between the Player's Handbook and the Monster Manual on the amount a creature can carry and still fly is covered by this question.)