A f/oss wiki with a much nicer UI than Mediawiki. Built on top of the Laravel framework, uses MySQL as its back end. Runs more like a book or notepad than a wiki (books -> chapters -> pages), so it has a really clean UI. Full search. WYSIWYG editor, but is also Markdown enabled. Relatively lightweight, doesn't require a huge server, just a bitty box. Local auth as well as the usual socnets.