HowNotToUseAWikiDon't over-categorize. Rather than inventing a complicated structure of categories from the start, as MemePit advocates, just chuck everything onto one page. Only bother splitting out separate categories when they are big enough for this to be worthwhile.
WikisAreNotUsenet. If you're having a point/counterpoint discussion in a Wiki then you're using the wrong medium; go find a better one. Wikis work well when you produce coherent documents, not when you use them as a third-rate usenet substitute.