can the fog atmosphere thing be made to float near the ground? 

as far as I can tell, it only makes the whole scene white-ish.  which I can't think of a use for.

they used ground smoke a lot in the old Lost in Space tv show. danger will robinson, danger

Do you mean Depth Cue, in the Atmosphere node? This works simply by adding the depth cue colour to the diffuse colour of the surface being rendered, at a strength depending on its distance from the camera.

So I'm fairly sure the answer is no, it can't.

I have seen a prop smoke/fog product, but I can't remember where.

Wait!

There is a way you can have the DepthCue effect stronger near the bottom of the image, and weaker towards the top. Just plug an inverted v_Texture_Coordinate node into the DepthCue Color channel.

It may need lots of tweaking, maybe with extra math nodes for positioning, to match the ground in your scene, however.

Hmm... just ignore my suggestion above. I discovered (should have realised) that it applies the gradient to each separate material that it renders, not to the whole view.

See also:

http://www.runtimedna.com/forum/showthread.php?t=35521

and

http://www.renderosity.com/mod/forumpro/showthread.php?message_id=3412281&ebot_calc_page#message_3412281

The second one I posted a shader with precise control of the fog height and variation. Useful when you know you want it exactly X inches above the ground.

Shader setup is there.

Stewer is being helpful answering questions today. But some days he's busy.

I just wanted to point out, as I've done before, that the quickest way to get a material question answered is to assume I've already answered it. Please understand this is not ego - it's a simple fact. You can find topics with answers fast this way. Not necessarily every answer in the universe, but it's a good bet for your first search.

Go into the forum search, and use "bagginsbill" as the author, both here and at RuntimeDNA.

That's how I found those threads above - searched for "atmosphere" with me as author.

But I really posted this test render because it demonstrates something I've noticed before about atmosphere rendering - both depth cue and volume - that I haven't seen explicitly mentioned anywhere else (although it most probably is and I just didn't find it).

It is that atmosphere rendering stops at the first raytrace bounce. So no volume is visible in the reflections.