The Wikipedia article on crowdsourcing suggests both "community-based design" and "open call". You might consider perusing the rest of it for other ideas.
Excerpt:
Crowdsourcing is the act of outsourcing tasks, traditionally performed by an employee or contractor, to a large group of people or community (a crowd), through an open call.
For example, the public may be invited to develop a new technology, carry out a design task (also known as community-based design[1] and distributed participatory design), refine or carry out the steps of an algorithm (see human-based computation), or help capture, systematize or analyze large amounts of data (see also citizen science).
http://en.wikipedia.org/wiki/Crowdsourcing
