A friend of mine shared his collection of esoteric sites online. Lots of good stuff here, and some of these sites are also listed in the sidebar. Feel free to add to it!
A Collection of Esoteric Sites
Internet Sacred Text Archive
Hermetics.org
Magic E Books
Twilit Grotto: Archives of Western Esoterica
THE GNOSTIC SOCIETY LIBRARY
Bulfinch's Mythology online
The Alchemy Web Site
Mystic Library
The Golden Dawn Library
Esoteric Golden Dawn Library
Rosicrucian Library(CR+C)
Classic Rosicrucian Texts
Popul-Vuh
Online Thelemic Texts
The Equinox as PDF
The Golden Book of Wisdom(posthumus)
The Growth of Man-Savartha
UT Library-Electronic Books
The Online Books Search Page
Internet Classics Archive
A Brief Study of the Rose Cross Symbol