There are no books officially banned in the United States, though specific titles are frequently challenged in school curriculums and public libraries. In the early '90s http://www.cs.cmu.edu/People/spok/most-banned.html, the American Library Association recorded over 6,000 challenges. And while the First Amendment protects printed materials, it's safe to assume the American government wouldn't appreciate a dirty bomb instruction manual. Certain types of sensitive information are restricted by law. Banned Books Online http://onlinebooks.library.upenn.edu/banned-books.html offers a brief but fascinating overview of banned books in this country. Some perennial banned favorites include "Of Mice and Men" and "Huckleberry Finn." Lately, the "Harry Potter" series has generated controversy due to its use of magic and witchcraft. Every year, the American Library Association sponsors Banned Books Week http://www.ala.org/ala/oif/bannedbooksweek/bannedbooksweek.htm, an effort to raise awareness of censorship issues. They also offer a list of the most frequently challenged books http://www.ala.org/Template.cfm?Section=pressreleases&template=/contentmanagement/contentdisplay.cfm&ContentID=57115 of 2003. http://ask.yahoo.com/20041108.html

None that I am aware of, as this would be a violation of the First Amendment of the US Constitution. Certain books are banned from some places (particularly public schools and libraries), and some private retailers refuse to carry others.