The open source augmented reality server, or POI (Point of Interest) search. In its simplest form, it takes a database of points with latitude/longitude, and a search request at a given latitude/longitude, and returns the points sorted by distance.
OSM XML to CSV conversion. POI only, polygons (and polylines, but not recommended) are approximated by centroid. Result is a 3-column table with lon, lat and value (for a particular key to be chosen beforehand).
This PHP script allows You to plot bubble charts on Google Earth. Have Your data in a query, view, table with fields: folder, name, latitude, longitude, radius, color, additional data. Set the DB parameters in the config file, and enjoy the results.