Given that I keep coming across interesting sources of data then I figured I should collect them here. Please note that just because I have listed them does not mean to say I have used them or that they are safe and free of malware. So, please take all the "usual" precautions.
Some of the following are data files and others are API endpoints.
There are also search APIs, see Brave Search API | Brave for an easy to use API that allows internet searching.