Other such websites where you can legally download free e-books are the text archive of The Internet Archive, Page by Page books (all books can only be read online), CMU's Universal Digital Library and Munseys.
Some websites require certain software, most of which are free to be installed on your computer. Popular formats in which e-books are published include DjVuLibre, Adobe PDF (I suggest you get Foxit Reader to read such files because Adobe's PDF reader is usually quite sluggish when it comes to handling big e-books with a lot of pages), Microsoft Reader
For now, you can't read new books that are out in the market as of now like Harry Potter or Da Vinci Code online for free but I'm sure in a couple of years as the books become less and less popular (if thats ever going to happen) we might find them online too. You're best bet for finding such books would be to check out your local library and find out if they have an online e-book service. Most libraries now offer e-book downloads to their patrons free of charge, but if it's not available in their collection you'll just have to wait.
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