[tag=path]Doom/ZTerrain[/tag]ZTerrain is command-line tool which generates terrain from heightmap (grayscale BMP) and stores it into WAD as ZDoom level. Then you can cut&paste it or only parts of it into your level. You can also test the generated wad itself, but before you do, you have to build nodes for it. Generated levels work in ZDoom 2.0.91 and higher.
Visit
official ZDoom forum thread.
Download here.
For making heightmaps you can use
Nem's Terrain Generator (to save the heightmap as bmp use
File->
Export->
Heightmap).
