I've recently come across something called Terra Incognita. It's an online fractal generator of basic terrains - mostly sea and a few varieties. Below shows a portion of this fractal map:
Zooming into the red rectangle, you get more detail:
I tried importing the image direct as a heightfield and got a rough inverse of it!
That's interesting, but not very practical. Because it's an image map it's "spikey" and useless to work with. I could use the images as a drape and probably will as a guide to implied mountains. I'm lazy, I like the coastlines generated by this. Any ideas about how to import these so that I can get coastline I can play around with?