New Documents Illustrating Early Christianity (10 volumes), Eerdmans.
I came across this set while reading Ben Witherington's The Letters to Philemon, the Colossians, and the Ephesians: A Socio-Rhetorical Commentary on the Captivity Epistles. It would be extremely useful to the study of early Christianity to have this set available in Logos.
You can vote for it here.