The debate over whether videogames that depict violence, namely Mortal Kombat, Grand Theft Auto, Kirby's Dream Land, etc., incite violence in otherwise nonviolent people.
There's also the issue of, rather than inciting violence, games desensitize players into a lulling acceptance of it. See Virtual War for how videogames might be changing the psychology of soldiers of war.
Whether or not violent games actually nurture violent people (studies show it is doubtful1), the debate has led to censorship and threatening legislation throughout the developed world. See Alex's blog for several thoughtful entries regarding the censorship of games released in Australia.
