in races of faerun there's a combination of two feats that allow any Aasimar or Tiefling to fly You might ask your dm about allowing these for any outsiders though.
Celestial Bloodline [General]
Some of your latent celestial abilities have matured.
Prerequisites: Aasimar, base Fortitude, Reflex, and Will
saves +1.
Benefit: You gain the ability to use protection from evil three
times per day and bless once per day as spell-like abilities with a
caster level equal to your character level.
Fiendish Bloodline [General]
Some of your latent fiendish abilities, inherited from an unusually
powerful fiendish ancestor, have matured.
Prerequisites: Fey’ri, tanarukk, tiefling, base Fortitude, Reflex,
and Will saves +1.
Benefit: You gain the ability to cast protection from good three
times per day and bane once per day as spell-like abilities with a
caster level equal to your character level.
Outsider Wings [General]
You have sprouted wings appropriate to your heritage, revealing
the power of your supernatural bloodline.
Prerequisites: Aasimar or tiefling, base Fortitude, Reflex, and
Will saves +2, Celestial Bloodline or Fiendish Bloodline.
Benefit: You gain wings (feathered if an aasimar, batlike if a
tiefling), allowing you to fly at your land speed (average maneuverability).
A medium or heavy load that would reduce your land
speed reduces your fly speed a proportionate amount.
