I hate DRM, but I don't have a problem with it for rental services (you don't own anything this way, after all).
There are some paper book Netflix-type services - a few have died, but apparently a few are still around.
http://www.booksfree.com/available_plans.shtml
2 at-a-time $14.49 2 (1 book orders)
4 at-a-time $17.99 2 (2 book orders)
6 at-a-time $24.99 3 (2 book orders)
9 at-a-time $32.99 3 (3 book orders)
12 at-a-time $40.99 4 (3 book orders)
15 at-a-time $50.99 5 (3 book orders)
Book ship via media mail (notoriously erratic in delivery times...low priority mail).
Just pointing this out...
I think a rental service of some sort, ala Netflix, would be very enticing. However, I doubt they would be willing to do it any time soon. Netflix has been working on getting the industry to accept them for years, and they still get in spats with the various movie companies (look at the common 30 day hold on new movies now, for example).