Crowdsourcing - Tracking the Rise of the Amateur - This isn't a space or prize site, but there is nevertheless an overlap. Here's the Wikipedia definition of crowdsourcing:
Crowdsourcing is a neologism for the act of taking a task traditionally performed by an employee or contractor, and outsourcing it to an undefined, generally large group of people, in the form of an open call. For example, the public may be invited to develop a new technology, carry out a design task, refine an algorithm or help capture, systematize or analyze large amounts of data (see also citizen science).
The term has become popular with business authors and journalists as shorthand for the trend of leveraging the mass collaboration enabled by Web 2.0 technologies to achieve business goals. However, both the term and its underlying business models have attracted controversy and criticism.
You can see the overlap between prizes and crowdsourcing, and in fact the Wiki article uses prizes and models like that of Innocentive in its examples. There are some non-prize space examples too! Even beyond this subject-level overlap, though, crowdsourcing is of interest in the prize field when considering open source prize teams like FredNet, public prize forums, the Commercial Space Wiki, typical prize development phases with public comments on rules, amateur prize teams, blogs with public comments, and more related trends.
So ... the Crowdsourcing blog link I gave above is one way to keep track of ideas and trends that are relevant to a good portion of innovation prizes and prize efforts.