The Milford Memorial Hospital Auxiliary will take your books. They have a fair every year to raise moeny for new hospital equipment and have a large used book sale. Contact http://www.bayhealthfoundation.org/index.cfm?fuseaction=cms.page&id=1003
If you are interested in the Axuliary of Milford Memorial Hospital, please contact Cynthia Jones at (302) 270-1842

The AAUW (American Association of University Women) accepts books for their annual book sale, "Dollars for Scholars," which funds scholarship assistance for women returning to school. Great organization, great people. (I have no connection with them, aside from being a happy patron at their sales.) More info here: http://www.aauwwilmington.org/donatebooks.html