The best way to bring a huge number of traffic is SEO = Search Engine Optimization. There are lots of tricks and tactics in SEO what we all know, more or less.But as per my opinion SMO, Social Media Optimization, is the latest trend to bring a huge number of traffic to your site. Facebook, Google Plus, Pinterest, Twitter, StumbleUpon, Digg, LinkedIn .. many social bookmarking sites, Yahoo answers, Forums are the main source of huge traffic. If you will do your SMO work seriously, then you can get unique and huge number of visitor per day. not only the traffic but also, Social sites can help in a various way in terms of SEO. There are lots of tricks and tactics will do with these kinds of sites.
Hope this helped you.