Be sure to not miss the final Appendix section, even if his Voronoi approach might not be the best approach for your particular map-generation needs (it really depends on your game IMO), there's a TON of links to great resources on various map-building topics: Technical things on Voronoi/Delaunay comp.geometry, general map building stuff for RPG/geofiction, Biological tables for determining plausible biomes, Geology references for plausible terrains and even a site on how to do pretty relief shading like is done on classic topographical maps!