Interesting. Those branchy ridge shapes look a lot like Diffusion-Limited Aggregate patterns. But then, I guess they didn't call it "universality" for nothing :)

They also reminded me a bit of GIMP's "Solid Noise" rendering with the "Turbulence" setting switched on. I rendered one, and turns out it doesn't quite look as good (cough), but now I wonder whether this would give a bit more realistic height map: http://imgur.com/oRlZ191

On the other hand, like you say, for terrains for videogames are always best generated by taking any of these algorithms, and mercilessly tweaking the parameters, post-processing, etc until it just looks sufficiently good. Actual physical realism comes into second place (and it should, like most game physics).