1. Nobody wants to join an empty social site. Either do it yourself or pay some people in 3rd world countries to have multiple accounts on your site and make it look popular. Each story should have hundreds of votes and there should be 10s if not hundreds of comments, its better if there is heated debate or discussion going on in the comments
2. Once it has the appearance of being popular, Time to make it popular.
-You could pretend to be a ron paul supporter and point out to other ron paul supporters that ron paul is getting the bad end of one your questions, and then 1000s of ron paul supporters would rush to your site to correct it.
-You could make a facebook app for it.
-You could do traditional advertising on other news or news related blogs.