The easiest thing to do with a big pile of old books, especially you’ve got a variety of genres, is to donate them to your local library. They will probably sell them to raise money to buy books they need. (These are great sales to shop at as well.)
Here are some other suggestions if you have a more specific collection of books:
If you have a collection of recent textbooks or other educational books, there are several organizations that collect such material to send to developing nations.
Illinois, Glen Ellyn: Book Rescue
Multiple locations: Project Night Night
Also consider donating your children’s books to your local school library or homeless/battered women’s shelter.
Books to Prisoners
I can vouch personally for Books Through Bars, one of a number of organizations that send books to prisoners. They offer a little hope to a desperate population, and help stave off bigotry through the written word in a place where racist groups recruit heavily. Their wish list reflects those in similar programs:
-Dictionaries & thesauruses
-Books in Spanish -African/African-American/Mexican/Puerto Rican politics, history and culture
-Books on yoga/mediation, martial arts, paganism, queer studies, and health — especially HIV/AIDS, Hepatitis C, and tuberculosis
See if there’s a prison book program near you.
California, Los Angeles: Lucky for you, the Last Bookstore now has a program called Re-Book It, in which they accept all your books. They sell what they can in their store and distribute the rest to local charities. They even offer free pickup!
California, Bay area: Regional list
New York, New York: Used Book Cafe. All profits from this bookstore go to Housing Works, a non-profit that provides housing and healthcare to homeless New Yorkers and those living with HIV and AIDS.
Super specific book needs
Texas, Houston: San Jacinto Museum of History Got a book on the history of Texas, and specifically on the Battle of San Jacinto? Give these guys a shout out! Here are titles they’re specifically seeking.
Releasing Books Into the Wild
If you have a title or two you’d like to share, you can leave them in a public place and post its location on Bookcrossing. Their intent: to make the whole world a library. Neat-o, huh?
Books Nobody Wants
Please sort your books before giving them away. No one wants your copy of A Catcher in the Rye with the peanut butter stain, no back cover, and eight pages missing from the middle. Nor do they want your Let’s Go Europe – 1988. These are candidates for the paper recycling bin.