Bailiwick Sim Raw File Editor
Bailiwick is an editor I've written for the .raw files used by Second Life sim owners to configure their sims. Its main purpose is to make it easier to edit the various channels of the raw file (there are 13). It's not a terrain editor, although it displays the terrain channels and can import terrain from Terragen or in image heightfields. It's officially still in beta. Feel free to download it and try it out.
Bailiwick Home Page