iDecide

iDecide helps you locate the most rational decision. The program uses the expected-utility theory to make predictions of which option you should choose.
iDecide will ask you to estimate how likely you are to succeed with an option, how much it's worth for you and how much it hurts if you fail.

It will then compute which option is expected to give most happiness. You might think that you don't need a program to make your choices, but research has shown that humans are surprisingly bad at picking the most logical choices. Useful or fun? You decide! Requirements
PPC, Mac OS X 10.2 or later
Related Links
Perversiontracker: iDecide 1.0 Useless Review