Ask HN: What is some information you're not able to find on the internet?
Did you specialize in anything and/or know about something where there's almost nothing on the Internet about?
If you asked 100 people who invented the monorail, most would say, "Walt Disney." Disneyland's straddle-beam monorail was invented by Goodell and was his second-generation design. The first design which ran in Dallas four years before Disneyland's was a suspended type.
I'm in the process of starting an online Goodell Monorail Museum precisely to fix this problem. I've collected hundreds of documents and photos from archival sources which have never been seen on the internet.
To a lesser extent, certain types of datasets can’t be found on the internet either. They may exist digitally, but they’ll never be sent across public networks.