This thread is for generically potentially useful stuff.
Here are genomes for some of my favorite algae strains, the Modern Lojban 5.3.6 Dictionary and Usage Guide, the Beginner's Guide to Glass Lenses, and Basic Hygiene from Alcohol to Wood Ash.
Additionally, my more mercantile contacts are usually pretty interested in buying [local reproduction rights to] art. I can offer a wide variety of media in exchange. I have plenty of stuff that doesn't reference high technology, such as "Henry V", the script of a play about an ancient monarch. (Consider this a free sample.)