Any bookworm would know that e-books are easily available anywhere online. Here are some that I know of; an e-book directory of sorts.
Download Free Ebooks
The eBook Directory
The Online Books Page
Free Tech E-books
This is a source for free dictionaries: Microsoft Reader
Personally, I don’t read e-books because I read more than enough online through blogs, and anything longer than a typical blog post hurts my eyes when I do want to read something e-bookish. Maybe if I had a Kindle I’d be singing a different tune… 🙂
If you’re looking for picture books, Lookybook is a one of a kind site selling books, in which you can actually read the book from cover to cover before buying it. Also, I think Flickr is a good place to search, as my friend Museditions found a slide show for her favourite childhood book, You Will Go To The Moon.