A project based at the University of Michigan and funded by a worldwide group of libraries.
As of 1 January 2015, three TCP collections are publicly available: Eighteenth Century Collection Online, Evans Early American Imprints, and Phase 1 of Early English Books Online.
List of current open access titles is at the bottom of the page. All are published under the Creative Commons Attribution-Non Commercial-No Derivatives 3.0 license.
"The SPO Scholarly Monograph Series is an interdisciplinary collection of original, open-access scholarly monographs and essays published by the Scholarly Publishing Office of the University of Michigan Library."
Lists open Access reprints from Michigan Publishing available online (at HathiTrust) or for purchase from Amazon.
Textbooks for Arabic courses (all levels, some specific to regional varieties) account for the bulk of the list. The remaining books are a mix from fields including psychology, political science, health sciences, and business management.
The Baldwin Online Children's Literature Project publishes online editions of classic children's books from the golden age of children's literature (1880-1922).