I've got a History of Christianity class next semester, and a little disappointed that none of my books are available in Logos. These are not obscure authors or publishers, but mainstream, awarded, and academic, like Oxford Press.
Diarmid MacCulloch's Christianity: The First Three Thousand Years
Documents of the Christian Church
Mark Noll, Turning Points: Decisive Moments in the History of Christianity I've suggested books by Noll before (as well as Marsden, Hatch, etc.), and there is one available. One.
David Bentley Hart, The new testament: A new translation I recall seeing other discussion about Hart here. This is new, so Logos gets a pass on this one 
