I mostly use Silo for modeling and have used trueSpace for rendering (I have version 6.x but 7 is now free). Somewhere around here is an old copy of Bryce, which has some nifty features...built-in terrain meshes and nice lighting and atmosphere.

Anybody remember Vistapro? I bought it back on the Amiga...first intro to DEMs. It was a pretty good piece of software. Think I found a version for the PC a long while back but I can't remember if it was freeware or something less-reputable. I never installed it so I can't say how it was.

Anyway, I can't imagine doing too much with regional maps in 3D. I expect they'd turn out very mechanical looking and I like a more painterly. For building, town, encounter maps, however, I can see 3D being a pretty cool medium. Here's hoping somebody proves me wrong on the regional map thing Maybe I'll give it a go if I ever get some spare time. Lots of projects in the hopper to get to first.
M