Pop Crunch has a list of sixteen great dystopian novels. The list, I think, inappropriately incorporates post-apocalyptic fiction wholly into the genre. Still, it has some interesting suggestions for future reads. One that's missing is Ayn Rand's novella Anthem, a marvelous assertion of the dignity of the individual.
Well, I guess that could then be taken as not dystopian, but it definitely starts out as a classical dystopia.
What books on the list have you read? What would you add to it?