Stem_Cell said:
Not by much - if your server supports some scripting language (that is, it's not just an HTTP server but has something like PHP), you can download a forum package. Installing is pretty easy most of the time.
I used to run a forum for no other reason than to have the experience. It never got large, as it was just me messing around with friends, but it was fun while it lasted. Ended up shutting it down due to time constraints - we were pretty much done with it, anyway.
I remember using <<
www.simplemachines.org/|Simple Machines Forums software>>. It's free, and I remember it being a real breeze to install and administrate. Granted, this was years ago, and I don't know how it's changed, but if you decide to do what Stem_Cell said, you may wish to consider SMF. Last I checked, they also had a pretty substantial collection of addons for the software that could add anything from basic image album galleries to a "reward" or "trophy" system.
There's also <<
www.phpbb.com/|PHPBB>>. I've heard good things about their software, but I've never used it. They're also free, supposedly.