AcidMaps is an open source library that generates interpolated images from a set of valued points in real time.
It's can be used to generate advanced visualizations with point datasets: (e.g.: sales, temperature, atmospheric pressure, population, etc...)
With the plugin for GeoServer (>=2.1), you can use a WMS points layer to generate an AMS map. You just need to add some additional parameters to the WMS request.