DId you know that Facebook has a limit to the number of people who can be added as "friends"? To be honest, I didn't, but apparently if you try to add more than 5,000 people, you're told that you've hit the upper limit. I suppose when Facebook was first dreamt up, the creators thought that no-one would add even one-fifth of that many links to their account, but Mark Cuban is one person who has. It's happened because Facebook is used quite a lot as a way of linking up with people that you might have something in common with, even if you've never met them or had a meaningful online relationship.