The OrigamiUSA Lending Library has moved from its old home (on a separate website) to OrigamiUSA's own website. You can find in the RESOURCES menu, or at this direct link:

http://www.origamiusa.org/lending_library

What is the Lending Library? It's a circulating collection of rare and out-of-print books that operates via U.S. Postal Mail. All OrigamiUSA members who reside in the U.S. are eligible to borrow books. See here for more details.