Same here. HTF is the only forum that I visit. I'm not really a "Forum" kind of guy. But my love for cinema, and the interesting people here keep me coming back. Plus, I can't leave until I find out what the hell silica is.
When I joined in April 2000 I didn't expect to last more than a few weeks before losing interest. Seven years later and I'm still here. The friendly people and atmosphere of the place caught me off guard.
I'm on about 8 different forums. Been on HTF for a long time (since Delphi, as was discussed in another place). But easily, without doubt the oldest forum I've been on has been one I've followed since 1986, started following it through USENet and just followed it followed it along. I still keep Forte Agent around just for it and a few other groups I'm a devotee of.
For about 15 years. Of course they weren't forums back then. I'm only on 2 1/2 right now that I read each day. HTF, AVS and [H]. There are about a half dozen more that I check up on from time to time. I used to help run a large forum (40k+ members) a few years back. That can suck up any free time you may have so I don't do that anymore.
I'll tell you one thing though, I hate forums now that use custom forum software that usually is so far behind the times in terms of functionality and ease of use. I much prefer vBulletin or clones up it such as phpbb and invision boards.
HTF exclusive for 6+ years now as well. I was a regular on combatsim.com (flight simulators) before that. I prowled newsgroups for a year or two in between. But the first internet community I joined was a Babylon 5 chat room in '97. Fun people.
I was very green back then, to the internet, the country, to english: I remember asking what " : ) " meant. I was told to look at it sideways.. to which I replied asking what "sideways" meant.
I am on a bunch of different forums... lets see, about 5 different hiking ones, about 3 different biking ones, 2 different paddling ones, 2 related to wood stove burning, 1 kind of general house stuff, and this one. HTF is probably one of my longest running forums though other than the hiking ones, a lot of it is hooking up with friends to take a hike though.