The top ten challenged books for 2005 show various themes, everything from homosexuality to violence to sexual content. However, just because a book is challenged at a particular library (school or public) does not mean it will be banned from that place. And these are just the books that are reported. Not all challenges are reported to the ALA Office of Intellecutal Freedom; in fact, the challenges reported are just a fractions of challenges that go on through the year (see last link). Unfortunately, when a book is banned from a place, the public loses. The general public of an area is deprived of having free access to a book, and the challenger has attempted to shut down the channels of intellectual freedom.
As a writer, I hold intellectual freedom close to my heart, for censorship can prevent so many things from being written down in fear of being criticized by the censor-loving public. In fact, Judy Blume, frequently-challenged author (yes, Judy Blume!), once said "[I]t's not just the books under fire now that worry me. It is the books that will never be written. The books that will never be read. And all due to the fear of censorship. As always, young readers will be the real losers." (source)
By censoring what we stock our shelves with, readers lose when we censor. Go forth and read banned books.