Are there any toolkits / libraries which can generate a world map and overlay data in a heat map sort of view (like Google's one on http://www.google.com/insights/search/#geo=&q=wimbledon+-tennis%2Cwimbledon+tennis&cmpt=q)?
I would need to be able to generate and display the map locally, not via some webservice, and would need the output in a browser (i.e. flash or HTMP/Javascript output).