I remember having found a web page which listed some research projects for freelancer programmers/teams. It was something like rentacoder.com, but it featured much more challenging research projects, and for much more money: rewards ranged from 10 000 dollars to 200 000 dollars. The bottom line is the projects weren't about implementing something, instead, they were about finding some way to solve a hard (usually AI related) problem.
Unfortunately, I lost its URL. Is there anybody who knows which site it is?