this was a rather long-winded post to ultimately plug a project you created. also, I feel like we get one of these a month, it would be helpful if the post explained why this one is better than any of the existing and/or failed attempts to do something like this.
Also, for some real advice, the reason these sites generally do not take off is despite the chorus of "ideas don't matter", people don't really believe that when they have what they think is a good idea. If someone has what they think is a million dollar idea they are apt to keep quiet and not want to tell anyone about it publically like this, and reveal it only insofar as it provides tangible benefits to them. Customer Development does not mean shouting your idea from the rooftops, anyway. There's a gradient between "I will tell you nothing unless you sign an NDA" and "I will post my idea to the public on the internet complete with a full explanation as to why it will work."