Best efficiency from grain crush?

What type of crush gets the best efficiency? I know you want the husks in tact, and all the other good stuff in the mash so it can convert. What I'm wondering is how much of the "other stuff" can you turn into flour? It seems to me that the finer the crush the better the extract will be, minus the husks because you don't want tannins. Is the only problem with a really fine crush a stuck sparge?

You are correct. The finer the crush, the better the efficiency. However, if you crush too fine (flour) you will get stuck sparges. You want to crush the grain to the point that you extract the endosperm without destroying the husk. You will actually get some flour and most of the endosperm will be broken up. The type of mash tun and false bottom/manifold you are using will determine how fine a crush you can get away with.
Here's a photo I found that Blender posted in his gallery that shows a good crush .

Thanks for the response!
I want to experiment with how fine of a crush I can make without getting a stuck sparge. I was thinking that if I could somehow layer the mash with progressively smaller screen it would sort out the husks and hopefully provide enough flow for the sparge water. OR sort the husks out with the screen (like for sand sampling) and then re-crush what is left. This is coming about because I'm not sure if the crush I've been getting is fine enough and the fact that I have a flour mill at home....plus it'd be a fun experiment. I just wanted to make sure that no harm could come to the grain from crushing it to finely.

You reach the point of diminishing returns rather quickly and sieving out the husks will almost guarantee a stuck mash. Cracking a kernel into 5-10 pieces is fine enough to allow all of the starch to leach out during a 60 minute mash.

If you do sieve out the husks, add them back in before mashing.

Oops, I meant to add that to the "OR, sort the husks out..." section above. I think the husks could act like rice hulls and allow the sparge water through. I imagine the wort will be very cloudy if lots of "flour" is used so I hope to incorporate a sort of HERMS method and recirculate the wort.