"The American Mathematical Society (AMS) was founded in 1888 in order to further mathematical research and scholarship. Since that time, they have embarked on a number of outreach programs designed to educate the public about the importance of various mathematical endeavors. In the past several years, they have been developing the AMS Books Online website, and it’s quite a resource. The works were all originally published by the AMS, and they can be browsed by author or subject. The subject headings include analysis, general interest, logic and foundations, and number theory. Users can download individual chapters from each book, and there are currently over thirty books available on the site. Visitors should make sure and check back, as there are plans to add books to the site periodically."
Source: The Scout Report from the Univ. of Wisconsin, Feb. 19, 2010