I don't know who's Flickr acount this is, but it's a pretty amazing one. They've uploaded loads of images of old American Adventure leaflets, etc...
Here's for anyone that's interested: http://www.flickr.com/photos/trainsandstuff/with/2992548855/
If you scroll back you'll also see a many more old leaflets and posters from other famous parks from across the globe, as well as some old Arrow Dynamics documents too.
Anyway, I enjoyed scrolling through all of the pictures and thought I'd share the account here too and let everyone else enjoy them too.
Here are a few smaller versions:
Edit: There's also some Alton Towers
stuff too, as well as an index for all of the theme park albums