Realistic terrain in 130 lines of JavaScript
Just a small note, not to sound snooty, just to educate people on what realistic terrain looks like...This is what midpoint displacement looks like as a heightmap:
http://imgur.com/ksETpO0,7gykFEV#0
This is what realistic terrain looks like (this is based on real-world heightmap data):
http://imgur.com/ksETpO0,7gykFEV#1That said, midpoint displacement, perlin/simplex noise, etc are good for modeling terrain at a less macroscopic scale and are plenty sufficient for the use of most games.