HyperCard combines graphics, scripting and persistence into an innovative approach to application programming.
I've started documenting stacks before. website 
HyperCard Pattern Language copied the look of Alexander's book while offering a few patterns of programming with an idealism to match the original.
People, Projects and Ideas captured the top-down authoring style that informed wiki years later. It was a who, where, what database about engineers sharing technology.
Greed in HyperCard prepared for an object-oriented programming contest at OOPSLA'89. I was quoted as saying HyperCard is object-oriented but you don't get to choose the objects.
Air Morse generated wave-shaped morse practice text intended for live broadcasts that never happened.
Gears computed the wheel ratio for each of my bikes. Included a simulator where you could pedal in each gear.
Wyatt Ride Guide provided a turn-by-turn visualization of popular rides using the non-linear view made popular as a New Yorker magazine cover.
I wrote many stacks for my kids. I would solicit requests which would be wildly fanciful. I would negotiate that down to something that fit HyperCard and would be interesting to do in an evening.
Good Bye Bad Giraffe was a story book where young Patrick made up the story.
Four-Function Calculator that worked on apples displayed on a table in a 3d image. Add and Subtract were always by one. Multiply and Divide were always by two.
Game of War expressed as a stack that played the card game by itself. All state was in fields which were organized into layers expressed as cards.
See also CocoaWorlds for more lost work based on apple products.