Note: The University of Minnesota's Open Academics project has a handy rubric for evaluating open textbooks.
Open Course sites for students and instructors, directories/portals, courseware, course builders and other tools.
"Purdue University Press is making available a collection of books published since its foundation in 1960 as Open Access PDFs. These titles are free to read online, download, and print for non-commercial purposes."
"The World Bank is the largest single source of development knowledge. The World Bank Open Knowledge Repository (OKR) is The World Bank’s official open access repository for its research outputs and knowledge products."
A great repository for out-of-copyright and in the public domain ebooks!