Archive.org is probably the biggest digital archive in the world, with interesting collections containing websites, games, books, videos, newspapers, music, etc. We personally love this special collection: The Pulp Magazine Archive.
Pulp magazines, also collectively known as pulp fiction, refers to inexpensive fiction magazines published from 1896 through the 1950s. The word “pulp” refers to the cheap wood pulp paper on which the magazines were printed.
You can read the pulp magazines in your web browser, but you can also download the pulp fiction books as ebooks in several formats. The only thing that you cannot download, is the smell of cheap old paper. (:-()