The Arena for Accountable Predictions or Long Bets site is:

…an arena for competitive, accountable predictions (Long Bets). 

…a forum for focused discussion and debate about prediction.

…an attractive tool for philanthropic giving.

…a way to foster better long-term thinking.

People making long term predictions and prepared to put their money where their mouth is. Some bets are a bit ridiculous though.

Update 2023: Some bets have already finished and from my observations most were wrong. e.g.

• Tesla will make a <$30,000 car by 2015, By 02022,

• Aether Physics (or its equivalent) will take the place of General Relativity and Quantum Theory,

• Turkish president Recep Tayyip Erdogan will be found guilty at a court of law or will flee from the country by 2020.

It would be good if the site owners made site navigation better and had a section for bets which have finished.

http://www.longbets.org/