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The Rosetta Project is creating an online collection of antique, freely downloadable children's books:

The Rosetta Project's collections currently contain about 2,000 antique children's books which were published in the 19th and early 20th century. We shall be putting these combined collections on line as funding permits. Our current goal of putting 2,000 volumes on line will create an online library of aproximately 65,000 html pages. However, as we are still collecting books from around the world, we expect the Rosetta Project online library to eventually reach millions of html pages.

Link via dollarshort.org