I've taken the open souce ext_calendar component (http://extensions.joomla.org/component/option,com_mtree/task,viewlink/li...) and made some significant modifications to it.  I cleaned things up fairly considerably for creating search engine friendly urls, and I ported the event administration to the back end.  My goal is to turn around and release this one to open source.  I’ll see if I can’t address some of the other user concerns and clean up the code more, but this could be/should be a nice contribution back to the open source