Library Genesis

aaaaarg.org

thepublicschool.org

library.memoryoftheworld.org

monoskop.org

Librivox public domain audiobooks

The Anarchist Library

Anarchy Archives

Audioanarchy audiobooks

Australian Poetry Library Tens of thousands of poems from hundreds of Australian poets (including talking poetry)

Biblioteca digital de la medicina tradicional mexicana

Macaulay LibraryThe Cornell lab of Ornithology - world's largest archives of wildlife sounds and videos

OpenStax College Free open source peer reviewed textbooks for college courses, by nonprofit organization “committed to improving student access to quality learning materials”