My pals Eric and Julia of Ramshackle Solid made acorn flour this year, and in their blog they showed how they did it.
Once the flour is dried out it may be a little coarse. You can put it in a cleaned out coffee grinder to get a finer texture. A good food processor also works and I am pretty sure they make attachable gadgets for mixers that really mill the flour if you get completely obsessed.
Our favorite use is acorn pancakes. Just mix the acorn flour 1/2 and 1/2 with wheat or other flour from your favorite recipe. I love the acorn flavor – slightly nutty, very hearty. If you make your own, let us know how it went.
I'm going over there uninvited for pancakes.