Like with cigarettes, I've so far managed to stay away from the "Sign Up" button despite all the Facebook invitations I've received over the years.
So far I never really saw the need to join it, since I figured that if anyone wanted to just have me listed as their friend so they can "broadcast" their messages, photos, etc. as their way of keeping in touch, I don't really see the person as a true friend.
For keeping in touch, I'm happy enough with e-mail, messenger, by phone, in person and sometimes the good old fashioned letter in the post. These methods still pass the evening away when there is little else going. For the time I want to broadcast something out in public, I write it in a forum post, like this one.
[b]Edit: [/B]I just saw Zathros' post. I certainly agree with you there, especially with Farmville. The clicker button on the family laptop is broken, which I'm sure is the result of all the clicking my sister in-law did on farmville. Even the cordless mouse goes through batteries every few weeks and it use to last several months.