From the Humanities E-Book News Blog:
Our most recently signed collaborating publishers, who will be contributing to our upcoming title release in summer 2014, are Southern Illinois University Press, Baylor University Press, Michigan State University Press and University of Toronto Press.
The number of publishers who have elected to work with HEB now stands at 112, including both university and some commercial presses. All content has been vetted by scholars and/or consists of books that have won prizes in their fields.
Direct to ACLS Humanities E-Book Web Site