I have always liked looking for hidden Mickeys, I will even make them using my spare change for a quick Mickey fix at home. A quarter and 2 dimes will form a terrific Mickey!
When you take the Living With The Land ride at Epcot you can often see this hidden Mickey in the aquatic part of the tour. Makes me smile, every time.
And if you ever use the women's washroom (sorry Nick) just outside of the Cirque du Soliel theatre at Downtown Disney, you will see this Mickey - set in tile. I actually did a double take when I saw it, as it is actually cut and set in tile, not stickers on top of the tile.
And this great Mickey head is somewhere in the Africa section of the Animal Kingdom, I was so excited to find it that I took the photo without really paying attention to where it is. Now I look for it every time I go, haven't found it again. Next trip!
And finally there is this hidden Mickey, it has been seen by very few people and you won't see it at any of the parks . . . unless I am there. Yes, I am a big enough Mickey fan that I have a tattoo! Sorry for the blurry photo - turns out it is very difficult to take a selfie of the back of your own ear.