I had heard of the Hidden Mickey field guides to DL and WDW maybe several years ago. On my last trip to DL in 09 i don't think I saw anyone with them, but ealier this year in WDW I saw maybe 20-25 people with them. I'll tell you about the book.
http://www.amazon.com/Disneylands-H...=sr_1_2?ie=UTF8&s=books&qid=1272339362&sr=8-2
It is narrow but tall so it can fit in a back pocket. It has a map of the locations in DL, DCA. It also talks about them in DTD and the park hotels. It has a scavenger hunt in the book where it gives areas to look for them and points for difficulty. It also has hints for a bunch, ruins the game aspect because these are more detailed directions.
So let me summarize a little section of the scavenger hunt. It says go to POTC and hop on. Then it lists the HMs on the ride.
One on Davy Jones 5 pts.
Mickey on the beach 3pts.
On wall first fight scene 5 pts.
Near end of ride in armor 5 pts.
After exiting ride find a HM on a door 2 pts.
It's all in order and has a few other general tips as well.
He also catergorizes an HM as a intended hidden mickey. So, not say, the flower garden at the entrance or the center of Mickey's fun wheel.
I'll just say it awesome and some people get really into using this book in the parks.