According to one Oxford professor's theory, the number of actual friendships a person can maintain is restricted by the human brain — and he quotes that number at 150. Facebook, on the other hand, allows for 5,000 "friends" for an individual account. I try hard to impose rules about whom I'll add as a friend (remember the whole "should I friend my boyfriend's sister" debacle?), so I have under 300 friends. And I have to admit, whenever I see someone with 1,000 or more friends, I get a little skeptical. I haven't run across any close friends who've hit their 5,000 Facebook limit, but with all of the crazy privacy controversies and changes, I'm afraid to have more Facebook friends than I already do. How many friends do you think is too many?