Better than Google Books!
Cornell's membership in the Hathi Trust Digital Library allows searching full text of recent copyrighted materials as well as older public domain works. Very useful!
As a digital repository for the nation's great research libraries, HathiTrust brings together the immense collections of partner institutions. It was initially conceived as a collaboration of the thirteen universities of the Committee on Institutional Cooperation, the University of California system, and the University of Virginia to establish a repository for those universities to archive and share their digitized collections, and quickly expanded to include additional partners with fast growing treasure of digitized collections.
Library of Latin texts (CLCLT). Texts from the beginning of Latin literature (Livius Andronicus, 240 BC) through to the texts of the Second Vatican Council (1962-1965).
Thesaurus linguae Latinae (TLL) Largest Latin dictionary in the world, but also the first to cover all the Latin texts from the classical period up to about 600 A.D.
Bibliotheca Teubneriana Latina (BTL) All editions of Latin texts published in the Bibliotheca Teubneriana, ranging from antiquity and late antiquity to medieval and neo-Latin texts. Each year, the database is extended by the texts of the newly printed Latin editions of the Bibliotheca Teubneriana.
Tessarae Developed to allow exploring intertextual parallels. Latin, Greek, English.
digilibLT Late antique texts.
Patrologia Latina Text of Migne's Latin Church fathers.
Patrologiae Graecae Text of Migne's Greek Church fathers.
Thesaurus Linguae Graecae (TLG) Comprehensive digital library of Greek literature from antiquity to the present era.
Early English books online (EEBO) Covers 1450-1661.
Evans digital edition (American Imprints) Books printed in the US during the 17th and 18th centuries.
Eighteenth century collections online (ECCO). English-language and foreign-language books, pamphlets, broadsides, ephemera printed in the UK and the Americas, between 1701 and 1800.
ARTFL Full-text online of nearly 2000 French texts seventeenth to twentieth centuries.
Gallica Includes many digitized collections of primary sources originally published in the 19th century.