Video by Jeff Howe, who coined the term “crowdsourcing”:
The Role of Non-Monetary Incentives in Crowdsourcing and Social
(link contributed by Iyad Rahwan)
Slides from a talk by Andrea Wiggins surveying incentives used in citizen science projects
Motivation by Design: Technologies, Experiences, and Incentives.
Open Street Map uses a seemingly much more limited points and badges system. Here is the info from https://help.openstreetmap.org/faq/ (retrieved 2012-09-24).
When a question or answer is upvoted, the user who posted it will gain some points, called “karma points”. These points serve as a rough measure of the community trust in the user. Various moderation tasks are gradually assigned to users based on those points.
For example, if you ask an interesting question or give a helpful answer, your input will be upvoted. On the other hand if the answer is misleading it will be downvoted. Each vote in favour will add 15 points, each vote against will subtract 1 points. There is a limit of 200 points that can be accumulated per question or answer. The table below explains karma requirements for each type of moderation task.
Extrinsic, Intrinsic, and Social Incentives for Crowdsourcing Development Information in Uganda: A Field Experiment by Michael G. Findley, Madeleine C. Gleave, Robert N. Morello, Daniel L. Nielson