[bugsy]

It depends on a lot of things!

We'll assume that whatever it is you are having people do is something that is intrinsically rewarding, benefits them, and is not taking up their entire life. We're not talking about having interns come in and work 8 hr days on projects you specify for no pay and you retain original copyright ownership as work for hire without pay. It's more like Stack Overflow answers.

As has been pointed out, in such a system by offering cold hard cash, you can and will attract gamers and the wrong element by paying, and you can and will also destroy the intrinsic motivation of the many sincere people who enjoyed contributing for free before.

At some level of contribution there needs to be pay off though, especially if you are directly monetizing contributions. I am thinking of youtube here. There are now professional youtube performers, people who make a living writing original comedy and commentary and skits for youtube and earning money from the shared ad revenue. This is only done with top earners who are making enough from ads to actually be able to fund doing it as a full time job. The result has been higher quality material and more stickiness from popular contributors.