Baen Free Library: http://www.webscription.net/c-1-free-li
Baen Promo CDs: http://baencd.thefifthimperium.com/
University of Virginia etext repository, LIT and PDB, mostly:
Gutenberg Master all-in-one downloads:
They also provide a custom CD/DVD download service:
Munseys.com - pick your preferred format; they have most of 'em:
The Universal digital Library (aka, Million book collection):
(Ever wonder what DejaVu is for?)
http://craphound.com/ Lots of good free stuff but also at the forefront of ebooks, their distribution ect.
http://nomediakings.org/ Much like Cory above but heavily into comics as well.
Some free SciFi Ezines.
a very good site :
Here is one that seems to be getting better all the time