While running social at Canpages, I did three things:
Increased blog traffic 25x by building a team of internal bloggers, integrating blog posts from freelancers, soliciting guest posts, and using Helium for hyper-local posts in 5 key regions.
Built out our profile on the most important social networks (Facebook, Twitter, YouTube, Google+) and grew our fan/follower base 10x. More importantly, by focusing on topical, interesting, and geo-targeted messages, I grew our engagement rate 100x.
Finally, by integrating social into our site, I increased traffic from social networks by a factor of 15.