Seems like I ran across this awhile back, but I can’t seem to find it now.
Isn’t there a way to accentuate darkness in the nooks and crannies of, say, a furniture piece. Sort of like ambient occlusion, but more pronounced, as if there was accumulation of dark stuff there.
As Wobi said ambient occlusion will help you achieve this effect. Ambient occlusion (ao) is basically a shader which applies shadow to an object according to its proximity to another objects - your described nooks and crannies are in close proximity to other objects and therefore will be more shaded.
I just did the quick test which you can see below - the material for the teapot on the right has a Mental Ray Ambient/Reflective Occlusion map as a mask on a Blend material. You can achieve the dust effect by reducing the samples in the ao map.