I've been using TiddlyWiki for some months successfully: http://www.tiddlywiki.com/ http://www.tiddlywiki.com/ Very simple (single HTML file, web server not r

I've been using TiddlyWiki for some months successfully: http://www.tiddlywiki.com/ http://www.tiddlywiki.com/ Very simple (single HTML file, web server not required), local, lightweight, can sync with Dropbox easily. For teams, we're heavily using the Open Source version of Etherpad. Not a wiki, but a great collaborative text editor.