One note I'd like to clarify. Then I'll shut up and let the creative poeples do thier thing.
when we're talking about rewards, these are rewards the player that is giving out the quest has on them, and not say something the system generates. if it's the latter, then I see easy abuse of it.
guy 1: "hey wanna do this quest for me?"
guy 2: sure, what do i have to do?
guy 1: kill a rat and i'll give yeah some monies
guy 2: sounds easy enough
*guy 2 kills rat*, system gives them 1k and 30 pp's worth of experience points.
with the easy of creating alts, someone could abuse that badly.
I am quite interested in this concept though. if done right, it would make things quite fun and open up quite a bit of possibilities for rp stuffs.