Is anything off-limits as a subject for art? Is there anything we're not ready to deal with as a culture? Should there be?
All of these are questions raised (or at least addressed) by a great article in Wired called "I, Colombine Killer" about a video game which puts you in the perspective of the Columbine shooters. It's a great read, and it will really make you think about the uses to which art can be used.