I use it to share funny pictures and news bits with my friends. Other than that, I don't use it a lot. I do hate it when people take it as serious business.
ANd when they do, one of my good friends and I troll the person out of existence.
For example, one of our friends who says it's serious business made a group so he could "Say whatever he wanted." He then invited all of his friends. My friend and I were 2 of these people, and made it our goal to post as many stupid links and worthless comments within a small time period. Combined, we had left around 59 stupid comments and links, and we were promptly kicked from the group.
Good times.