Upon arrival at the activity, place all the books in a pile. As people arrive, invite them to place books in the pile and grab a book (or two) they'd like to take home and read.
During the activity, share information on your favorite books -- books that have touched your life, books that are hilarious, books that made you think, or whatever.
You may want to invite some people to come prepared to share information on their favorite book to get the ball rolling.
Box up the leftover books and donate them to your local women's shelter, children's hospital, or good will.