Dig through the HN archives... I'm pretty sure that some variation of the basic idea of "a platform for sharing ideas that people want to give away" has been developed about 100 times over the past 10 years or so. OK, maybe not quite 100, but this seems to come up fairly often, and I'm pretty sure I remember more than a few people saying "I'm building a site to X" where X is pretty close to the above notion.