It's a huge compilation of weird technologies and inventions. Most of them are crackpot, of course, but some of them are legit and truly fascinating. Rex Research predates the Internet, you used to have to order from little ads in the back of Popular Mechanics. Back then this was pretty much the only way you could learn about this stuff. Nowadays some of the less crackpot tech is more widely known, and some of the inventions even have their own Wikipedia pages, e.g.:
Hilsch-Ranque vortex tube "a mechanical device that separates a compressed gas into hot and cold streams. The gas emerging from the hot end can reach temperatures of 200 °C (392 °F), and the gas emerging from the cold end can reach −50 °C (−58 °F).[1] It has no moving parts."
http://www.rexresearch.com/ranque/ranque.htmhttps://en.wikipedia.org/wiki/Vortex_tube
Maxwell's Demon! Although it does not violate thermodynamics.