We are in the process of helping libraries obtain a wide selection of books from the world's major religions in electronic (e-book) form. We began to collect copies of the reference materials that are in the public domain. 
Almost immediately we realized that it would be much more effective to compile the links to reliable sources that offer hundreds of these religious texts, often for free. This project will continue to grow as we discover new sources.

http://www.religion-online.org/  This site has more than 6,000 articles and books. Topics include Old and New Testament, theology, ethics, history and sociology of religion, communication and cultural studies, pastoral care, counseling, worship, missions and religious education.

http://www.theharmonyproject.org/sacredpaths.html  Introduction to the sacred path. A detailed description of Taoism, Christianity, Baha'i, Buddhism, Confucianism, Hinduism, Islam, Judaism, Shamanism, Sikhism, Taoism.

http://www.sacred-texts.com/  A huge collection of sacred books from all of the world's religions. Available free to the public.

http://altreligion.com/ Lots of interfaith links along with full texts of religious books from many faiths.

http://www.levity.com/alchemy/texts.html Hundreds of religious, spiritual and metaphysical books.

http://www.religioustolerance.org/other_es.htm Interfaith links and resources

http://www.adherents.com/adh_influbooks.html  Major Scriptures, religious texts and influential books.

http://www.gnosis.org/   A comprehensive library of Gnostic scriptures, including the Nag Hammadi Library, as well as a large selection of writings and documents relating to the study of Gnosticism. For over a decade, the Gnostic Society Library has been the principal internet resource on Gnostic tradition.