Since first steps (or types:) with PC I was dazed with various CG landscape applications. First was old Bryce 2 (that pretty quickly grows to v4), then I saw Terragen, my favo for almost two years. The big relief from single sheet editing comes with Mojoworld application from Pandromeda - fully procedural based CG engine.
At current moment Mojoworld is my hobby :)
But You're welcome to visit my webpage TerraEscape for more images and Zazzle posters.