View source for Motivating Good and Bad Actors

Two challenges relating to motivation face those who organize online collaborations: how to motivate good actors to contribute and how to motive bad actors to either conform to regulations or to cease from participating. 

'''Motivating Good Actors''' 
The success of online collaborative efforts such as Wikipedia and Couchsurfing (among many others) depends entirely on the participation of massive numbers of users.  What motivates individuals to participate? To not just use such services but to actively contribute to their upkeep? And how can developers change the structure of their efforts to best motivate greater numbers of users?

'''Motivating Bad Actors'''
The fact that online collaborative efforts are open and available to massive numbers of users and participants also means that they are susceptible to mis-use by bad actors. Bad actors may act maliciously (e.g. editing Wikipedia to include false information) or simply out of ignorance.  How can such actors be motivated to conform?  Alternatively, how can such actors be eliminated or dissuaded from acting at all?