Free/Open Source Forum Software

I have a thing for vanilla - especially the feel of the smooth, silky pods and the scent of the tiny black seeds. They sell vanilla pod bundles like these in the chaotic food markets in Madagascar - so the word 'vanilla' makes me melt! Vanilla costs a small fortune in SA - but not in Madagascar, where it sells for almost nothing. It would seem that this "almost for nothing" characteristic is carried over into some Forum software. Imagine my absolute surprise and wonderment when the web designer I had met with, pointed out that free/open source forums existed and they could be customised! This had simply not occurred to me. Perhaps if I had spent more time on the Design and Development phases of Instructional Development, I would maybe have figured this out! One of the freely available forums is one called 'Vanilla Forums' - it looks and sounds awesome! I have the bad habit of being swung by a name (I have just chosen my new bicycle frame colour, partly because of the name - moondust grey! hehe) - so I thought it best to investigate if there was more to this software than just a pretty name!  A short search later, and bingo - there are stacks of free/open source forums available, and it is probably just a matter of figuring out which one will meet our requirements in terms of the forum objectives. Check out this forum and wiki comparison site: http://www.forummatrix.org/. It compares things that I have never heard of, but probably need to start understanding!