From a young person, I found out you can murder people in The Sims. (I don't play it myself.)
What you do is place stoves in each square around the unfortunate victim so they can't move, then turn all of them on. And here I thought the worst you could do in the game was be mean and/or fornicate. Silly me.
I'm told there is criminal activity in Second Life as well (with real money involved).