I was on Overdrive this morning trying to remember what book I was wanting to search for* when I see some new links. In the spirit of curiosity and dead cats, I clicked. Overdrive is now offering DRM-free books. So, when they have a book that has a DRM-free version, it is called Open epub/PDF and has a cute little green, unlocked padlock symbol. The version that has DRM has a red, locked padlock symbol. These unlocked books still have a due date but I'm not sure how they can even enforce that without DRM. Now, there aren't a lot yet and the vast majority seem to be from O'Reilly but the fact that it's now one of the offered formats is, in my opinion, a tremendous step forward. I did get myself on the waitlist (yes, ridiculous, artificial scarcity, yada) for 3 Stargate:Atlantis official fanfiction books.
*Seriously, I have no idea what it was but I remember thinking about it and being really excited so I hope I eventually remember.
ETA: The vast majority on the first 3 pages were from O'Reilly but it looks like it's mostly science fiction with a couple of romance thrown in. Of course, this is my library so ymmv.