I'm going to be a bit cynical here, so excuse me in advance...
Why is death considered to be a penalty? Have you seen what trying to live here is like? Bullshit religion, crap music, boring politics, the illusion of money, purile corporations, never-ending conflicts over timeless squabbles and Jersey Shore. You realize that there is absolutely NOTHING stopping us from ending our own lives? People do it all time, every day in various methods by the hundreds. Sometimes voluntarily. Yet, all people seem to do is either mumble and grumble about meaningless methods and ideas that will offer no REAL solutions, or they will continue to exist in a state of stupor-like acceptance and continue to live in a world where they are made to believe they are powerless to change the situations they are in for the better.
I say, if someone does something that causes you strife, have 'em listen to that god awful Macy Gray song in an infinite cycle until that someone ends their existance on this plane of reality. Unless, they like Macy Gray. Then you make them watch an endless amount of YouTube clips with cute animals doing cutesy type things.
Of course, if you want to kill said person - fine by me. Just make the death somewhat entertaining, record it and put it on YouTube. I subscribe to that kinda stuff.