Let’s see, I’ve tried a lot of these, here’s what I’ve found…
vBulletin - (as far as I remember, php/mysql) seemed a little cryptic for customization, but not bad.
phpBB - (php/mysql) My favorite forum backend, wonderful support, addons and has a very straightforward interface.
YaBB - (perl/cgi) Older engine, lots of support, but not as configurable or understandable as most.
YaBBSE - (php/mysql) Nicer, but not quite as many features as phpBB.
openBB - (php/mysql) Couldn’t ever find much information on this.
As for forums that you don’t host yourself, I liked the one supplied by chatarea.com the best. If you have any questions regarding setting these up, toss me a line and I’ll try to be of service.
phpBB is a very good one… I like the way that they lay out the administrative tools and such, I also like the whole forum look, but its not the best look.
I’m personally an Invision Power Board fan, although I also like phpBB.
Regarding the licensing issue: It is my understanding (based on the documentation to the IPB sitting on my computer) that you could run an IPB for free, but would not be entitled to any support or upgrades.
Just a note about ProBoards: On the online “NationStates” game I play, many people have had their passwords stolen by unscrupulous forum administrators, as it’s not difficult for a ProBoard admin to get one’s forum password. So unless you really trust the administrator(s), I recommend against registering on ProBoard forums.
Recently IPB has stopped handing out their forums for free, you can get a demo by installing stuff on your computer (you also have limits on posts and such).
Anyways, phpBB is skipping their 2.2 version update and decided to hop into version 3.0.0 – to compete with other bulletin boards.
Now, here is the tricky part. Are you running a Linux or Windows server?
Pretty much, I love phpBB2, and it is free. www.phpbb.com
If you are running a Windows server, all you need to do is create a blank Access 2000 Database, and post it where the instructions tell you to. If you are running a Linux server, it does not accept Access 2000, and you must create a SQL database. Comes with very detailed instructions for both.
Instead of using something like access… you might want to just install MySQL as your database. Setup is pretty simple, and if you learn to use php and MySQL on your site, you can create some nice content (Like pulling news from a forum), even without the fourm, its a nice combo.