Well, no need to do more research, someone else has already done for you. And it is not me!
So check out the following links for a rather comprehensive list of Wikis as well as a nice comparison:
Links:
[1] http://linux.philosweb.com/drupal/category/it/software
[2] http://en.wikipedia.org/wiki/List_of_wiki_software
[3] http://en.wikipedia.org/wiki/Comparison_of_wiki_software