make a new camera and a poly cube (or whatever.. a locator will do)
parent the cube to the camera,
write an expression on the cameras DOF distance (or whatever that attribute is called O_o)
the expression should look kinda like this:
-(cube1.tz) = camera1.dofdistance;
this will connect the z position relative to the camera of the cube
to the dof distance of the camera
now when you change the dof distance in the cameras attribute editor (try holding control and click dragging in the number input box), the cube will move to where the DOF starts.
this makes tweaking the DOF a breeze
that point will be where the cameras focus is.
the other attribute, Fstop, is the distance infront of and behind that point where stuff remains in focus..
also you can can connect other DOF features to the cube too
like Fstop to the cubes scale z
but thats the most helpful one..
im at work now so im not 100% sure that all the names are correct.. but if you get stuck drop me a line
edit:
oh yeah, remember to set the cubes transforms to 0 after parenting it so it right on top of the camera..
. If anyone has ever modelled something like that, like torn off skin.. can you post a wireframe shot and a shot of what it loooked like finished, really close up? Ok, cya.
. It now has a bone texture and looks quite good if its a big enough render. you cant see the cracks in the bone unless its a large render either... which is kinda correct. Anyways, heres a link to the image.. i didnt want to hold up the 56k'ers.
. Were thinkin the same way 
