Corpus Inscriptionum Latinarum
Numen: The Latin Lexicon
Inscriptions of Israel/Palestine Brown Univ; includes Hebrew, Greek, Latin, and Aramaic inscriptions
U.S. Epigraphy Project Greek and Latin Inscriptions in the USA

Perseus Digital Library by Gregory R. Crane, Tufts University; Greek and Latin texts in original languages and translation

Lexicity links to online language resources including Latin—not sure how useful it is