Here are a few links that I have in my bookmarks (a couple may have been posted already):
http://www.blackmask.com/page.php?do=page
http://www.ebooklocator.com/ - Locate eBooks
http://www.ebookexpress.com/default.asp - Make your own
http://www.ebooks.com/ - Supposedly one of the largest sources for ebooks
http://www.memoware.com/ - have not really looked at this one, but I had it in my bookmarks
http://cebooks.blogspot.com/ - again another one I have not been too
Thats what I have.
McCade