One thing this misses is how to make plateaus: it uses a power law to make plains at zero altitude, but those end up getting flooded. Whereas real geography has plains at sea-level, flat seabeds, high-altitude steppes/prairies, etc.

There was a nice recent paper in JCGT that dealt with using noise to model terrain. It does a nice job of creating gently rolling hills.

Modeling Real-World Terrain with Exponentially Distributed Noise (http://jcgt.org/published/0004/02/01/)

Red Blob Games (run by Amit P) is an invaluable resource for anyone wanting to learn about making game maps, pathfinding, noise functions, and other related concepts. I especially recommend his article on polygonal map generation. I used his work on grids as a starting point for a hexagon-grid map generator written in Haskell which my friend and I worked on this summer.

Wow, that was really well done. I could follow along with the concepts and code and near normal reading speed. I look forward to playing with those ideas.

Amit is very good. His site is an invaluable resource, I hope Stanford never takes down his pages.