Prove that you had a specific document at a specific time. Store your data in an open database. Uses IPFS for storage, and Ethereum for notarizing the data.
Library for having the computer pick your exact hex color codes so you can say "I want this to be red" and have it look good (accesible).
What if you take a JPEG image and then compress it again and again and again and you get to watch it as it happens. Maybe it'll look like one of those timelapses of decaying fruit. That could be something, right?