This is a great place for all things Disney! Hidden Mickeys are the famous "mouse ears" shape purposely "hidden" into different things at WDW: architecture, props, scenery, etc. There is a whole thread somewhere on this board just on that subject! (you can do a search from the menu bar). Anyway, once you get into looking for them, it can be addicting!
(and just as a "by the way," you can get a counter that goes out over a year from TickerFactory.com!!...our trip is over a year away, too!).