Game coding

/frog/, I'm writing a 3D game and I need help with the logic.  I'm trying to model the ability to walk around anywhere on earth.  In order to do this (& keep it interesting), I need a map generator.  I have the temptation to model it after minecraft's block generator, but I don't want to have a blockly terrain.  It should be regular terrain, like Elder Scrolls or Halo.  Does anyone have an idea about how I would do this?

tl;dr: how do I make a normal map generator?

Generating a map with the kind of knowledge you seem to have (i.e. you haven't googled procedural terrain generation), the last thing it's going to be is interesting.