The music of Disneyland, and all the Disney parks for that matter, available on iTunes! Disneyland has a musical catalog that is recognized globally. There is a huge market for this, from the vacationer who wants to pick up the "Small World Theme," that is still stuck in his head a week later, to the die hard Disney fan that just wants those hard to find tracks to complete their collection.
The company has been really good about promoting the park music, the 6 disc "Musical History of Disneyland" in particular. Also itunes featured some previously unreleased albums from Walt Disney Records for their 50th Anniversary. Definitely steps in the right direction.
The ultimate still remains the "music on demand" feature that was in the park awhile ago where you could compile your own CD from a really wide selection of audio from the park. The great thing about it was that it ranged from the obvious songs to the most obscure background music or ride spiel. A deal with iTunes could top it all!
Why stop at music? I also think there is a market for Park related video. There is a ton of attraction related media that is no longer a part of the parks that is literally sitting on a shelf. Why not make some money off it and make your fans very happy in the process. I'm sure the Disney fans would pay $2.99 to get "Captian Eo" or the "America the Beautiful" circle vision film onto their iPod.
Ah... if only Disney had an "in" with Apple!