The Internet Archive has made available a new classification of its extensive library that it calls "Folkscanomy: A Library of Books".
Folksonomy: A system of classification derived from the practice and method of collaboratively creating and managing tags to annotate and categorize content; this practice is also known as collaborative tagging, social classification, social indexing, and social tagging. Coined by Thomas Vander Wal, it is a portmanteau of folk and taxonomy.
Folkscanomy: A collection of books and text derived from the efforts of volunteers to make information as widely available as possible. Because the metadata related to these scanned books are often done outside the library or cataloging industries, finding material can be more difficult. The Folkscanomy collection attempts to add a layer of classification for easier navigation.
The collection is classified in a large number of sub-categories. I'm sure you'll find many that interest you. A few examples in alphabetical order, with links to them:
many more at the link. Interesting, entertaining and engrossing reading.