Google Books and Hathi Trust
Hathi Trust and Google Books are two large, ongoing projects whose goals are to create accessible e-archives of books from around the world.
Although there is much duplication of content between these two archives, each has unique items.
Hathi Trust has a better search than Google Books.
Full text will usually be available for items published before 1923 (cutoff date in US copyright law); full text may or not be available for more recent publications, depending on the wishes of the copyright holders.
