As such, we thought we'd alert you to some of the following resources for getting free Kindle books on your new device (as well as your smartphone and desktop). For all but the Kindle Store, you'll need to transfer the books manually using a computer and USB cable.
Project Gutenberg: 33,000 free e-books, including all of the classics, available in Kindle, HTML and simple text formats.
Google E-Bookstore: The free section is filled with thousands of free, scanned copies of books, available in Kindle-friendly PDF formats.
Internet Archive: Millions of primarily rare, out-of-print works in multiple languages and formats (including Kindle), especially useful for academic work.
Open Library: 20 million user-contributed items in multiple editions and formats (including Kindle).
ManyBooks.net: Nearly 30,000 titles, many of which have been pulled from Project Gutenberg. Has a good collection of little-known Creative Commons works.
LibriVox: Thousands of free audiobooks.