http://www.d20srd.org/srd/classes/druid ... usandFaces
I feel like this should be fairly easy to wire into the game, given that currently there are changes in polymorph system.At 13th level, a druid gains the ability to change her appearance at will, as if using the disguise self spell, but only while in her normal form. This affects the druid’s body but not her possessions. It is not an illusory effect, but a minor physical alteration of the druid’s appearance, within the limits described for the spell
Another thing that might be wroth looking at is sigil's implementation of alter self. That one allowed to fully specify appearance - face/haircut index and color, race, etc.