LinkedIn is a social media site for professionals. It's a far more serious, buttoned up, high powered environment designed to facilitate networking and getting ahead in the professional working world. This power networking site is growing rapidly. It boasts over 100 million members, there were over 2 billion searches on LI in 2010, 69% of LinkedIn users have an income of at least $60k, 74% have a degree, and 68% are over the age of 35. Source: onlinemba.com