What do you get out of social media?

I have recently started two internships involving social media to create buzz and use it to market companies. I eventually want to start my own business consulting firm and do online branding for local businesses. Most likely will get involved in a niche like the restaurant industry.

I was just wondering what is it that compels you to get on facebook, to use fluther, and all of the other sites you may be on. Personally I am just now getting involved with twitter and I find it absolutely fascinating