A free archive of US Army field manuals for the downloading.
A utility that, when given a grammar and syllable system, can generate words and phrases in languages that don't yet exist. This is meant as a utility for linguists for studying languages, but I can see applications for gamers, specifically prop-makers.
A publisher reprinting rare, forgotten, and unusual texts. Download them as .pdfs or purchase them online. Many categories are represented, from epic sagas to classical fiction, drama to architecture, history to technology.
Occult texts and grimoires in e-book format.