As I mentioned in my previous post, I have a cleric in the party whose vows prohibit him from taking anything which is not earned. I have decided to award him xp for the treasure he does not take, because, to me, the xp awarded for treasure is an abstract representation of a successful adventure. Last session, at the tail end, the party captured a chest containing 3,000 electrum coins. (Randomly rolled) The party received this treasure after a long evening of planning, stealth, tactical prowess, and a fair deal of luck in clearing out a bandit stronghold. They didn't get all the treasure (some bandits escaped, taking most of the easily portable look with them), but I would say the experience award represents the tactical exercise of taking on superior numbers and prevailing.
So, I was thinking: perhaps I should adjust the xp award to be equal to the monetary gain from the adventure. This seemingly meaningless change in semantics does one thing for me: it prevents the other characters from getting bonus experience because their shares are bigger due to the cleric often not taking one because it would violate his vows.
Now, as for the excess treasure itself (1/6 of the total take), perhaps the party deserves it. After all, they will likely be traveling with an under-equipped party member. Case in point: the cleric is currently wearing studded leather armor.
Now, if I implement the other experience system I'm working on (or just use the wonderfully simple one volunteered by Timeshadows), there will be experience for sessions where the cleric's vows cause him to to be at a disadvantage, but let's burn that bridge when we come to it, eh?