Bibliotheca Augustana - Index of Latin literature. Navigation is in Latin: you can browse alphabetically or by century. Also includes German, English, and Greek literature.
Perseus Project Latin Texts - With accompanying English translations and links to dictionaries, commentaries, grammars, and other tools.
A good sized collection of Latin texts. Unfortunately, all but Boethius' Consolatio Philosophiae and Ovid's Metamorphoses are restricted to use by students at the University of Virginia.
Latin, classical, medieval and modern; texts, symposia, grammatical aids, Attic Nights of Aulus Gellius, Res Gestae of Augustus Divus, Erasmus, and Philobiblon of Richard de Bury in Latin
CELT is a resource for contemporary and historical Irish documents in literature, history and politics. This particular link takes you to their collection of Latin texts.