e-book app Gutebooks (in addition to their audio app), but it seems to have been deprecated (I'm no longer able to connect to the server on my copy (which I only got 'cause there was an in-app purchase to fund Project Librivox).
FWIW, Barnes & Noble has been plundering the public domain using a book composition/keying house in the Philippines to make their public domain books which they make available in their stores --- Amazon apparently has a similar setup for the Kindle Store:
https://www.amazon.com/Public-Domain-Books-Kindle-Store/s?k=...
Rather a shame that PG didn't monetize by putting their books up there pre-emptively.