Would this be a legal idea for a Web site?

What if there was a site that handled personal wagers that people make? The site would take money in advance from each party and would pay the total to the winner. Determining the winner would be easy in the case of events from the news. In other cases, both parties to the wager could agree on a set of one or more third parties who would announce the winner. The idea would be to prevent people from welching on wagers. The site might be able to get by without making any charges, making interest on the money that it holds.

Another possibility would be for the site to be used to record small loans between people in order to keep a record, so the person loaned the money would not be able to deny it. I don’t know how the site could make money on this other than through ads.