I hate it* and don't use it with any sort of regularity, but I have an account. Sometimes people tag me in photos and I check them out. Maybe once per month. Also, some people sometimes invite me to events through it. I wish people would use better photo hosting services and event management services. They exist, so I don't see Facebook as a necessary evil, but rather an unnecessary and mediocre service.

*That's actually a very strong word. I dislike it, but I don't lose sleep over it at night or anything.