There are many social media sites which boost the traffic. But Facebook, Twitter, Youtube, Pininterest, Orkut Google+ and Linkdin are considered the best among them. But signup or creating account on these sites is not enough to drag traffic towards your website. Promotion depend on network, Groups and Followers on these sites.
Apart from that your account can be banned for the violation of rules & regulation for the promotion of the product. So first you would need to read the terms & conditions of these sites then keep the rules in the mind when you are promoting your website.
But still there are rare chance to get any lead from these social networking sites as real visitors come from the search engine.