The Corpus Inscriptionum Latinarum (CIL) provides a comprehensive collection of ancient Latin inscriptions. A number of CIL volumes are made available on scanned pdfs by the Berlin-Brandenbergische Akademie der Wissenschaften.
Almost all of these inscriptions may be located on the Epigraphik-Datenbank Clauss-Slaby. The initiator of the database is Prof. Manfred Clauss.
h/t Chris Zeichmann
Biblical Studies Online 