A Java application/library that can generate PNG tile overlay images for Google Maps from multiple data sources. Inactive because there are better alternatives: Java - http://geotools.codehaus.org/ PHP - http://www.mapserver.org/
The CHIP Cluster Generator attempts to create spatio-temporal cluster data in an automated fashion to help evaluate epidemic detection software. The spatio-temporal data will then be used to determine robustness of spatial detection algorithms.
A planet-wide terrain generator, using simulated tectonic movements rather than fractals. Intended to produce richer information than just a heightmap - geology layers, climate, biomes, and resources.