Talk about online books seem to be a very frequent topic of conversation in the search world today. In the past few weeks we've not only posted about the latest with Google Book Search/Google Library Project, the Open Content Alliance, and new stuff coming from Amazon and others.
I once again want to mention and incredible browsable and searchable database, The Online Books Page, of books in the public domain (including Project Gutenberg materials) that's been edited by John Mark Ockerbloom since 1993. The OBP currently lists more than 25,000 titles.
Listings can be searched or browsed by authors, titles, an subjects.
Finally, John mentions that he is adding some public domain books from Google Book Search. He has also added the "first demo batch" of books from the Open Library, sponsored by the Open Content Alliance.
When I'm asked to name some of the most impressive tools on the open web, the OBP is consistently near the top of the list.