A great piece on NPR recently on How To Save A Public Library: Make It A Seed Bank where a partnership between the Basalt Public Library (CO) and the Central Rocky Mountain Permaculture Institute have created this wonderful seed bank.
There are a few other seed bank libraries as well: A past blog post from July 2010 on Richmond (CA) seed lending library. Rebecca has a blog - www.richmondgrows.org - on creating your own seed lending library and San Fran now has two branches lending seeds!
Other libraries like Fairfield Woods Branch have a seed to seed series; Alameda Free Library also offers similar service; and East Palo Alto Seed Library has started a seed lending library partnership with Collective Roots.
If you know of more libraries with seed lending services or banks, please comment or email me!