Corpus Scriptorum Latinorum - - Online texts from Augustine to Vergil, sorted by author and including links to Latin, English, and foreign language translations.
Electronic Text Center Latin Resources - - 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.
LacusCurtius: Latin Texts - - The main index page for the Latin texts on LacusCurtius: Pliny's Natural History, Frontinus, Vitruvius, Ptolemy's Geography.
The Later Latin Society - - 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 Lati.
The Latin Library - - A collection of Latin texts: classical, Christian, medieval, and modern, including such classics as Lewis Carroll's "Gabrobocchia".
Latin Texts at CELT - - 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.
The Library - - A library of Latin works, with introductions and translations (Dana Sutton, U of California).
Lupa - - Helps for searching for classical texts. Navigation is in Latin.
Nordic Neo-Latin Literature - - A searchable database of Neo-Latin (1530-1800) literature from Nordic countries.
A Private Library - James O'Donnell - - The classification system in this library is not very intuitive, but if you dig, there are Latin, Neo-Latin, German, and English texts here.
Project Libellus - - Free Latin and Greek texts with certain redistribution restrictions.