Alex Tabarrok blogs about assurance contracts, an idea he originally wrote about in the 90's. An assurance contract helps get around the public goods problem.
In an assurance contract people pledge to fund a public good if and only if enough others pledge to fund the public good.
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What a dominant assurance contract adds is that the entrepreneur agreeing to produce the public good if k or more pledge also agrees that if fewer than k pledge he will pay a prize to those who did pledge.
Many companies have used the power of the internet combined with assurance contracts to create new businesses. Groupon assures businesses that if they engage in a promotion they will have a minimum number of customers, while Kickstarter and Indiegogo fund products or ideas that can be closer in nature to public goods because without the funding many of the projects they support wouldn't exist. The existence of a product in the market place that large groups of people would wish to purchase isn't the most common example of a public good, but it seems to qualify even if the good itself is a private good.
It is important to note that Kickstarter figured out a better way than dominant assurance contracts to fund their projects. Rather than forcing entrepreneurs to risk large payouts to potential funders (or arbitragers who can seek out projects certain to fail), the Kickstarter business model is to provide extra benefits to funders. They allow project creators to offer different levels of rewards, depending on the choice of the funder. The rewards can be capped, so only the first X amount of people to fund at a given level are given significant rewards while late coming crowdfunders will get slightly inferior rewards that are still better than what the general marketplace will get.
This is a solution where all sides benefit (assuming the people kickstarting the project didn't miscalculate their rewards), so perhaps the type of contracts used by Kickstarter and other crowd funding platforms should be called Pareto assurance contracts.