I have made a free landscape editor for use with truevision3D. It paints on the landscape using 3 Splat textures and a base texture, comes with pre defind texture library and you can make hills and dips , flatten land. Its beta and still needs a lot of work. It has an easy to use XML format project file and a slick user user interface.
It is beta and I need people to give me feed back about the program. Right now it only allows very_low landscape precision but you can do unlimited chunk size, depending on your video card and system specs.
Please give me feed back on this this thread, There will be a forum for it pretty soon too on my own site
http://3dmapeditor.hostoi.com/ Here are some screenshots:
Like I said its beta, so there is not much to it at the moment, but there will be more features in the near future to play around wiht.
Here is the download link for it, my download section is a little buggy at the moment.
http://www.filefactory.com/file/ahb560e/n/3D_Map_Editor_3_0_Beta_rar