So, Jenn wants to cut down on the number of books we own

and switch to having those books in digital format. Obviously a huge minus here is the cost, but she suggested offhand that it'd be nice if she could scan in the books we own, convert them to a txt file, and just upload them.

Some of those books are out of print, actually. If we're doing that for our own personal benefit, and not to share with others, is that actually illegal? (Not that we'd be caught at it, any more than if we simply typed up the contents, but that's a different question.)