perhaps off topic -- wiki/forum web apps

Hi. This might be a bit off topic. I apologize. I'm trying to find any open source "php" webapp that would have Wiki/Forum/Member functionality. The app can be Wiki based, and able to extend via adding "Forum", or it can be "Forum" and able to extend via adding "Wiki". Or, it might be a separate app, ,and I might need to then remove "stuff" I don't need. I've been looking all over the net, with no success! If you have any idea about this, please ping me! thanks -bruce