A couple of weeks ago, Bjørn Sandvik pushed out his thematic mapping engine: http://thematicmapping.org/engine/. It's a nice and simple tool for classifying and visualizing the freely available United Nations OneStop Data.

Unlike most other theming engines, it also handles time very well. I generated a time-history thematic map of internet users around the world and temporally visualized in GoogleEarth:

Internet users per 100 Population - Temporal Earth from mapufacture on Vimeo.

Check out his other tutorials and information in the blog about using GeoJSON, KML, databases, proportional symbols and more.

Bjørn is continuing to tweak the engine and is in discussions on the OSGeo mailing lists about the appropriate open-source license under which to release the engine.

It's great to see some really compelling next-generation web-based and usable geospatial tools emerging.