The Centered Librarian points to The Online Books Page at the University of Pennsylvania, a listing of over 25,000 free books on the Web. While the site does appear to be indexed in Google, it might still be worth a personal visit if you're searching for something. Probably because it only appeared on the site recently, one title I searched wasn't listed at the top by Google, which instead pointed to Amazon, where it was available for $135, or Storming Media for only $37.95 as a PDF, while The Online Books Page pointed to the free PDF version on the FEMA site.
John Mark Ockerbloom has put a lot of work into this site!
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