At Epcot, in Japan, you may go in a choose an oyster that is guaranteed to have a pearl (sometimes 2, but rarely). These pearls range in size and color. You also have the option of buying silver/gold jewelry to place your pearl in, and of course the price of that ranges from reasonable (say $20 or so) to... well, much more expensive! I do it everytime I'm there!
Other special things would be to ride up front of the monorail with the driver, to get "pixie dust" put in your hair at the mainstreet barber shop. Watching Wishes while sitting practilly under the castle, Being one of the last ones out of the park on the monorail. And crying when you hear "when you wish upon a star"