Thesaurus Linguae Graecae (TLG)
A research center at the University of California, Irvine, has collected and digitized most literary texts written in Greek from Homer to the fall of Byzantium in 1473. Currently contains more than 105 million words from over 10,000 works associated with 4,000 authors. Users must create a profile in order to use the database. Click on the "register" link on the upper right to do so.