Futures market are a recent phenomenon related to the spread of the internet. Betting online becomes a predictive tool. They are based on an interdisciplinary mode of thinking, as developed in institution design. This model also lies on the idea of “collective intelligence” that was made popular by the book of James Surowiecki.
There are numerous websites, that are dedicated to betting on future events and that include political events. One of the great divide between them is related to money. For legal reasons, some of them allow players to bet “real money“, others, for the opposite legal reasons, would not. Futures markets have been used to predict the outcome of elections. See in the recent case of France. Some internet websites use online betting to create social networks, that can work as predictors and be a ressource for marketing companies.

Consensus Point
Foresight Exchange
Intrade
The Iowa Electronic Markets
Longbets
Newsfuture.com
Play the News
IARPA experiment