A better question to ask, I think, is what information is not available readily. Meaning, not in a machine-readable format, not complete, not up to date, not free, not from a reliable source, etc.<p>Something that I found this to be true for is basically every List_of_* Wikipedia article, the machine-readable format especially. But then if you look up the same information on WikiData it either doesn't exist or it's massively lacking in one of the points above.
It would be really great to have in-depth smart medical questionnaires that I can do in private app, so that when I go to the doctor, he can easily get all the information that's possibly relevant, in a very short time.