Nellisir
Hero
I agree that game wikis can be hard to navigate, but I think that's more an issue of the typical wiki structure: You're supposed to find topics through search or links, rather than an index. (In my game wiki (here, if you're interested), I've gotten around this by creating and maintaining an index page as a wiki topic.)
You don't notice that at Wikipedia, because it's so big you're going to get some sort of hit no matter what word you type into the search field. But it sure is noticeable in a wiki with just a few dozen pages. . . .
I've had a long and happy relationship with PBwiki, but they've moved towards a more "professional" audience. I was grandfathered in for a while, getting a platinum account for a basic fee, but I don't know what I have now except that I haven't paid and they haven't booted me.
Anyways, most wikis will have a "list pages" feature and a good search function, so indexes are less necessary.
I think the link is in my sig; I used it for campaigns and rules.