Pchart4mw extension for creating charts
code.google.com/p/pchart4mw
What Jamie wrote
Very good extension and doesn't require sending data anywhere. Uses internal PHP libraries. It works as a hook so you can embed Semantic MediaWiki queries inside of the call for the data. Awesome!
PHP chart for MediaWiki (pchart4mw) is a MediaWiki extension for visualizing data in different types of charts. Using pchart4mw's simple syntax you can create professional charts like bar, pie, line, radar, scatter and bubble charts, all within a MediaWiki server environment. pChart4mw uses the 'pChart Library', this is a free PHP Chart library able to create different types of charts. The pchart4mw extension serves as an interface between MediaWiki and the 'pChart Library'.