A recent post to the B-Greek list about the availability at the Internet Archive of the first and second volumes of The Grammar of the Greek New Testament by Moulton et al. reminded me that it had been a while since I'd done trial searches there for some keywords of interest (Latin, Greek, lateinisch*, griechisch* — and one nice feature of the site is that an asterisk works as a wild card).
Moulton and Milligan's useful study of the Vocabulary of the Greek Testament (1914-24) in light of the language of the papyri discovered in the late 19th and early 20th century and Moulton and Geden's Concordance to the Greek Testament (1897) are also available.
I was delighted by how many titles seem to have been added since I last poked around there, some (like Karl Staab's 1933 Pauluskommentare aus der Griechischen Kirche: aus Katenenhandschriften gesammelt und herausgegeben) still under copyright (published 1933). This is particularly surprising since it's currently in print. That title and quite a few other 19th and early 20th century German works have a notation "microform" or "microfilm," suggesting they've made their way to the Internet with film or fiche as an intermediate step. The page images I've seen are uniformly quite high quality, whether they've gone through filming or not.
Angelo Mai's edition of Codex vaticanus: Novum Testamentum graece ex antiquissimo codice vaticano (1859) is also at the site.
When I return to the Internet in a week or so after a trip to points north I hope to take some time to explore more extensively.