The Wiki link returns 404. After that all links with the exception of the Home link return 404 due to bad links from the wiki page as it returns "/wiki/link-you-requested" instead of just "/link-you-requested"
The wiki has been removed since it hasn't received much traction and did not really take off. We'd like to instead focus our efforts on revamping the rest of the site.
Good point regarding the link. We will remove it from the menus.