Punish Bad Users With Drupal Misery
If you're sick of banning or deleting troublemakers on your Drupal website, you might want to check out Misery, the module designed to give trolls a taste of their own medicine. Creating a random length delay for a user, redirecting them to a random page, presenting them with a 404 error, and crashing their browser if they're using IE6 are just a few of the things you can make users endure with Misery. I'm still waiting patiently for a Punch In the Nose module, but this is a good start.
So that would be...
If you want to give your trolls the silent treatment try the Cave module.
DailyKos has a better way to deal with Trolls. Enough downvotes and the system makes all their posts invisible to the rest of the users. The troll still sees them so he/she wouldn't know they're essentially locked out (at least not right away).