Neat idea, but the dizzy majority need not fear for their immortal souls! An "unfair term" in a contract or other legal agreement is unenforceable - it's one of the reasons why the Office of Fair Trading is investigating the banks and the charges they apply. You might sign a contract with, say a loan shark, that "allowed" the other party to kill you if you didn't comply with their terms - however, if the other party did kill you they'd be breaking the law. If they tried to sue you for the right to kill you, the court would rule against them.
"No, no, I don't mind being called the smartest man in the world. I just wish it wasn't this one." -- Adrian Veidt/Ozymandias, WATCHMEN