Huh. We have **lots** of digital books here...long boring story. Just so you know, digital books multiply and cross breed with hard copy books, so if you invest in an eReader, you will have more books (of both kinds) than you ever anticipated. We have all our bookshelves crammed, books piled on top, and books piled throughout our private quarters.
I had never considered creating such content, but it's a brilliant idea. <brain hums....>
As far as libraries, I have a card at a library (large system) that "lends" digital books. I have to "wait in line" until the title I want is available, then I have to download it, and then it turns into a pumpkin after three weeks. I can still see the file, but it won't open.
I don't know that sharing eBooks one has purchased is terribly feasible. I know that Amazon has a mechnaism to temporarily lend a book to a friend, but DH cannot open a file on his tablet that I purchased from a specific, non-Amazon distributor (SO annoying. What if my eReader crashes? I doubt I'll buy from that particular source again).
We've had many guests who have Kindles or some such...they come loaded with their own content for study or relaxation reading (whatever they're here for...).