Experience for your own actions
I only award experience to the character doing the action, whether or not he or she is under the influence of a mind altering spell. This is for direct action experience only.
If a wizard dominates someone and that person kills a creature, the wizard gets no experience, period.
However, if the wizard dominates a rogue and sends the rogue into a dungeon to retrieve a poweful magic item, while the rogue will get experience for all the traps and monsters in the dungeon, upon receiving the item the wizard will get "story" and "goal" experience which I give out as well in my game. The wizard my also get bonus "personal" experience for clever use of a ability, something I also give out in my games.
I find this to be the most fair and balanced. And since my characters are getting charmed and dominated a lot, they are quite happy to be getting the experience for their actions ... actually, they also often get bonus experience for good role playing of being charmed or dominated which isn't always easy, especially when other characters don't know and you aren't allowed to to let them know. It's usually some of the most entertaining sessions we have.