I was looking into forums for another site I am working with now... unfortunately, now that the price of WWWThreads/UBBThreads has increased, I am suggesting VBulletin to them as a viable alternative.
I love WWWThreads/UBBThreads and all, but the price for a new installation is quite high. Yearly access to the Members section on new accounts is Ludicrously high (This is a bigger factor than you realize. VBulletin only charges $30 for yearly access for *all* members).
My other alternative is to write a forums system from the ground up, which I am actually considering at this point.
