Here are some resources about Prediction Markets. I will analyize the possibility of their legality in China later.
According to Wikipedia, Prediction markets (also known as predictive markets, information markets, decision markets, idea futures, event derivatives, or virtual markets) are speculative markets created for the purpose of making predictions. Assets are created whose final cash value is tied to a particular event (e.g., will the next US president be a Republican) or parameter (e.g., total sales next quarter). The current market prices can then be interpreted as predictions of the probability of the event or the expected value of the parameter. Prediction markets are thus structured as betting exchanges, without any risk for the bookmaker.
People who buy low and sell high are rewarded for improving the market prediction, while those who buy high and sell low are punished for degrading the market prediction. Evidence so far suggests that prediction markets are at least as accurate as other institutions predicting the same events with a similar pool of participants.
Here are some populaprediction markets online.
http://www.biz.uiowa.edu/iem/
A group of real-money prediction markets/futures markets operated by the University of Iowa Tippie College of Business. Unlike normal futures markets, the IEM is not-for-profit; the markets are run for educational and research purposes.
http://www.betfair.com
The world’s biggest prediction exchange, with around $28 billion traded in 2007. Running sports predictions.
http://www.hollywoodstockexchange.com/
Virtual prediction game.
http://en.wikipedia.org/wiki/Policy_Analysis_Market
Policy Analysis Market was a proposed futures exchange developed by the United States’ Defense Advanced Research Projects Agency (DARPA) and based on an idea first proposed by Net Exchange. Closed because of the opposition of some politicians.
http://www.intrade.com/
Intrade allows bets on a wide range of future outcomes: political events (in the US, India, Germany, Israel etc.), climate change, current events (bird flu, earthquakes etc.), academy awards, science.
http://www.intrade.net/
Sister site of intrade.com. It allows the creation of custom markets.
http://us.newsfutures.com/
A prediction game in the form of a stock market, otherwise known as a virtual prediction market.
https://bet2give.com/
a charity prediction market where real money is traded but ultimately all winnings are donated to the charity of the winner’s choice.
http://ppx.popsci.com/
An online virtual Prediction market run as part of the Popular Science Magazine website. The application was designed by the same group behind the Hollywood Stock Exchange using their Virtual Specialist Application.
http://www.hubdub.com
A web-based prediction market in which players use virtual money to trade predictions on future events.
http://www.thestandard.com/
Having an interactive section where visitors can make predictions about the future of the tech industry.
Here is a paper on Google’s internal prediction market.