Soks is yet another Ruby wiki. See http://www.soks.org/view/Home%20Page (the link seems to be dead).
* Automatic linking between pages (no need for wiki words or any bracket shenanigans). * Easy to add, move and delete pages * Calendars, automatic summaries and the like * An api for classes to modify the wiki * Flat file storage (incidentally, this makes it easy to import from instiki using its export function) * Easy to edit the look of the wiki with per wiki templates. * Variety of ways of authenticating, with the authentication scheme selected based on a regexp of the page title. * Built in web server (No need for Apache) * Textile * Uploads and Images * RSS feed for changes to any page