The American Library Association (ALA) maintains a useful website of Banned & Challenged Books. It answers the questions such as to, "What is the difference between a challenge and a banning?" and "Why are books challenged?" It includes lists of banned book by author, by year, and by decade. There is also a link to statistics.
Each Year the ALA celebrates Banned Books Week:
"Banned Books Week (BBW) is an annual event celebrating the freedom to read and the importance of the First Amendment. Held during the last week of September, Banned Books Week highlights the benefits of free and open access to information while drawing attention to the harms of censorship by spotlighting actual or attempted bannings of books across the United States."
Lists compiled by the ALA: