The Internet Sacred Text Archive
Probably the most extensive single site on the Internet for sacred texts from all sorts of religions, including not only the great world religions but also ancient and indigenous traditions and "mystery" religions.
"This site is a freely available non-profit archive of electronic texts about religion, mythology, legends and folklore, and occult and esoteric topics. Texts are presented in English translation and, in some cases, in the original language."
(most material at this site is in the public domainh but some of it may be copyright by site author)