If you want to do it in a way that actually requires talent (ie. not just automatic filters and whatnot), you could do this: Make a new layer for the clouds. Airbrush them in white. Use the smudge tool to blend them (adding fluff). Alternately, paint the entire layer black. Change the blending mode to "Screen". Use the Dodge tool set to "shadows" . Fluffify with the smudge tool. Dodge the highlights for added brightness in the front which will help add depth. Mountains. New layer. Draw the shape of the mountains with the paintbrush tool in black or dark gray. Lock the transparency on the layer. Now switch to white. Bring your brush opacity down to around 15 or 20%. Go over the dark shapes with a few different natural-ish brushes. Continue until you've drawn the mountains to your satisfaction. Unlock the transparency and adjust the blending as needed.

I'm not overly well versed in Poser, but this might work. Start with your basic tone (I don't know if this would be 50% gray or a fleshtone). Use the burn tool (set to midtones or shadows) and draw the depressed portions (cracks if you will) of the wrinkles. Now draw over those, in a slightly larger brush size, with the dodge tool, and you should get something nice and stripey. (the lighter parts should be right up against the dark parts, with midtones in the areas in between wrinkles) Clean it up and add some more texture with a small-sized smudge, and they should look like wrinkles. As for the Poser portions, I have no clue.

Attached Link: http://www.eccentrix.com/misc/wonderzombie/index.html

Here's how I would do it... Use a brush that's got some sort of nice dotty texture to it. (in 6.0, the faux finish brushes work nicely) Add a new layer. Draw the basic shape of the trail. Don't worry if it overlaps parts of the fairy. You can erase the parts you don't want later. Use whatever color you want it to be when it's finished, only darker. (so if you want shiny glittery blue, use navy blue for now...) Now, use the blur tool (not the filter. it should be irregular) over the grainy dot stuff you just made. Once it's blurred, go over it with the dodge tool (set to midtones) using the same (or a similar) brush as the one you used before. Change the layer mode to something like "screen" or "color dodge". Now use the eraser tool (set to less than 100% pressure) to fade out the effect as neccessary. If it's too overbearing, adjust the layer transparency. That should pretty much do it.