SOAR Terrain Engine

This would be great for BMax. Even if not for commercial purposes.

http://www.cc.gatech.edu/~lindstro/software/soar/

If you're interested in a very fast LOD terrain engine you might want to check out the one in Unity2 once it's available. Regarding speed and easyness of use it will most likely beat everything in this price range.

It looks pretty efficient but I never understand any of the very advanced math in these type of PDF things.

It would be really nice if it was a realtime fractal landscape with infinite detail.

Problem with all the different methods is that you most likely want a solution which fits best to the hardware and there some strategies which were good a few years ago collide with how the gfx cards work best nowdadays. And this will change again once geomtry shaders are used more often.