I am looking for a 3d terrain engine. In particular, I need something that will create (or allow me to create) textured terrains (i.e. like Myth). This will be used in a realtime environment (objects will be moving constantly over the terrain).
I’d like something really simple to use, too much work @ work right now for me to get into anything too deep for a home project ;P.
There are some at www.j3d.org.
We use a simple heightmap divided into tiles so that the normal Java3D culling can remove most of the geometry from rendering. Textures aligned with the tiles are simple and additionally we use a detailmap. Very simple, straight forward and works fine.
Now it depends on your needs. Size, resolution and such. Out approach of course is limited in both, size and resolution 
The j3d.org code is not a terrain rendering engine in the true sense of the word. There is an implementation of the ROAM algorithm, and there are loaders for various terrain file formats, but it is not a complete engine that you could just drop into any application. It requires some work and you have to build your own application architecture over the top of it. It does handle very large scale environments and deal with texture tiling, but also a couple of known bugs too…