Whilst cracking WEP may be fun, doing it may be illegal, and can get the perpetrator into all sorts of legal issues ( read prison ).

If I found someone trying to break into my car, I would take a cricket bat to his knees, if I catch anybody trying to break into my wireless network ( presumably to steal something ) I will take similarly forthright action.

I suggest you keep your nose out of other people's business.

If you think you won't get caught, ask Randall Swartz ( perl guru ) if it's worth while - he's a well clever dude, and ended up with a prison sentence for his sins