Just wondering how people go about making believable ground fog and mist, preferably through the medium of metaclouds....but any advice would be helpful....

Thanks guys!

try a low altitude cloud layer - that works pretty well.  Alternatively you could put a box in the scene and give it a volumetric mat

Here's a scene where my night fog worked out pretty well, with some volumetric lights:
http://www.renderosity.com/mod/gallery/index.php?image_id=1446146

I tried MetaClouds and didn't get very good results. What worked for me was to create a fog "terrain" for the close-up low fog, add a custom fog material (started with one of the default fuzzy glows). Then I mixed that with a very thin spectral cloud layer above it, by moving the whole scene, plus the ground, up to the cloud layer altitude. The volumetric spot lights also have that artificial smoke feature enabled and the function for that tweaked.

This is what i did,In the first image I makde a layer and set it to 1 yard altitude, and 2.5 yards height,quite simple and more of a swamp type mist or fog found in nature,in the second image the same material is added to a cube, disadvantages are render times. The standard cloud layer takes longger to render but looks nicer than the cube and depends greatly on the size of your scene. You can of course add basic functions to getr a swirlie effect or more of a clumpy effect no problem.

...and the cube

 and here is the material if you wanna get in there and see the settings(; Just right click,save target as and change the suffix to .mat

oops

I use FrankT's method. The clouds settings provide a lot of parameters to get what you want. It's possible to get really close to real life.

IMO, the fog in jc's image is not very realistic. I think that is more smoke than fog. The scale in real life ground fog is much larger. See references below.
IMO, the fog from Trepz is too uniform, cuts the objects in a razor sharp way. See references also.

References:

http://k53.pbase.com/u26/pygmyhippo/upload/43825894.GoldenGroundFog.jpg

http://www.gordonanderson.ca/Balloon/b1/images/P9088579%20%20ground%20fog%20.jpg

http://pro.corbis.com/images/42-16796137.jpg?size=572&uid={DFFF8ADF-1D87-42BA-9F84-76D0216828F8}

http://tripcart.typepad.com/tripcart_the_blog/images/trees_in_fog_on_the_shepaug_river_by_ric.jpg

http://i.pbase.com/o6/29/454229/1/79394274.3CPXz5ls.Muhrlein_GroundFog.jpg

Well apparently you didnt read either of my posts as both of Franks methods are used here. Realism, no it isnt,  this is where it is up to the person top decide what type of function they wiash to use,this is just a VISUAL example for the poster.the mat file is right above where it says oops in my previous post btw...

If that's Frank's method, it's not a good example, IMO. My image was rendered in preview mode. I used the standard "low clouds", altitude to 0, height to 5 meters, cover 75%, all the rest by default. That sphere has a 6 meters diameter.

Thanks for the excellent fog photo references Rutra.

To me they show that fog in a close-up, like my scene required, is pretty much non-existent. Real close-up fog is a contradiction in terms. It's at most a thin haze - undifferentiated, even and not in the foreground.

So, I had to make imaginary fog - the kind Hollywood and stage shows do with dry ice and blowers. The horror movie type fog.

No doubt my imaginary fog could be improved a lot, but I don't think it could ever be photo-realistic, as your references demonstrate. That scene required "artistic license", rather than "photo-realism". These things are trade-offs which visual communicators have to decide on and go with.

I grew up in the swamps and have never in my life seen fog that looks like that outside of a Hollywood studio. But for art what you did is a better fog to use(;

I just look at them and there fabulous. I didnt say it didnt exhist...i just said i have never seen it :D Not trying to start a pissing contest over it all,just different strokes for different folks thats all(;

Thanks for the advice guys...love what you've done here, Artur....I'll have to give it a try!