Penguin Classics has a terrific program being offered at the moment through which you can receive a free randomly chosen book from their published 'classics' in exchange for a review that will appear on their Classics Blog. When you register, you agree to read and review your book within 6 weeks of receiving it, and then you'll get an email telling you which book was chosen for you. I've seen on Library Thing people getting books like Complete Poems of Samuel Taylor Coleridge and Memoirs of Hardrian. I feel really fortunate - my selection was The Sign of Four by Arthur Conan Doyle. Having never read any Sherlock Holmes, I'm extremely excited by this choice.
For more information, or to sign up for the program, go here.