Check the link below for additional details, and this site for an example (note that I haven’t tried it and don’t vouch for it)
There are already sites being set up so that people can request and trade a loan if the Kindle owner doesn't need to loan a particular book to someone close and wants a particular book. A Nook-book loan-trading forum has been popular for awhile. I imagine the publishers don't love this idea, but with paper books that often now cost LESS than the e-book versions due to publisher-pricing whimsies, those paper-bound books CAN be lent to one and all, and the paper industry has survived through the decades.
Now that more than one loan-trade site is being set up and I don't want to recommend (rather than report on) this, I've started you off if you want to investigate whether this would work for you and is fair to publishers (only one loan permitted per book would seem to take care of that problem though).
The sites are being announced on Amazon's own forums and you can find them if you search on "lend book sites" in the forum searchboxes there, on the right.