writes "BountySource is a hosted project management site for OSS, but unlike SourceForge or Google Code, BountySource incorporates code bounties directly into the bug/feature tracker. Other sites (like Bounty County) have tried to track bounties but have failed because they merely link to the bounty details and do not hold the money in escrow.
BountySource currently allows bounties to be placed using Paypal and has a built-in dispute settlement system. The site shows signs of beta software, but it's under active development and according to their roadmap they have some cool features in the works. Some major projects, such as ZSNES, have already switched to it."