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