I don't have one and frankly, I don't think I'll get one unless I have kids one day. I use the internet for lots of things, and I use the phone for lots of things, but there are times when I am unplugged and I don't want anything intruding on that. People seem to be obsessed with the damn things, and now that a bunch of them have Twitter and Facebook it's a hundred times worse. And don't even get me started on the iPhone (aka The Borg)... We let these things control our lives too much, and I won't be beholden to them. If I owned one people would expect me to use it, so I just don't own it.
Plus, I don't want to pay for it. You iPhone people are nuts - four thousand dollars over the span of your contract? You should be in a mental institution. It's a damn phone.