I am using XML/SWF Charts on my site. (http://www.maani.us/xml_charts/) You can see an example here: http://www.carhuntr.com/prices-Chevrolet-Suburban.html

It is easy to work with, and I have tested it using browsershots. Displays correctly in almost all browsers. My only concern is the load-time. So far it does not seem too bad.