I don't know why I didn't link to this sooner, but here it is. Pamela Ribon (pamie.com, Why Girls Are Weird) has been running online book drives benefitting public libraries and disaster-stricken communities since 2003. This year, she teamed up with David T. Cole (Television Without Pity) and launched the Dewey Donation System. The 2006 book drive benefits the Harrison County Library System, which was hit hard by Katrina. If you're interested in helping out, click the fancy button in my sidebar.
Edited to add: The button seems to have disappeared, but the code's still there. Hmm. Just use the link above, if you want to donate.