This is one of those sleep-deprived middle-of-the-night ideas which I'm reasonably likely to regret posting in the morning once I really wake up - but which, at least at the moment, thinking on my more-corrupted-than-standard hardware, seems like a cool idea.
Most role-playing games have a system for determining whether or not certain actions are successful or not. Most of the time, these can be described as setting a target number, and rolling one or more dice, with various modifiers - eg, you might have to roll a 13 or higher on a twenty-sided dice to correctly answer the sphinx's riddle, and having your handy Book of Ancient Puzzles to refer to may give you a +3 bonus to your die-roll.
How insane and awful an idea would it be to have an RPG system whose core mechanic wasn't based on linear probabilities like that... but, instead, on decibels of Bayesian probability? For example, instead of a bonus adding a straight +3 to a d20, or increasing your odds by 15% no matter how easy the task or how skilled you are, the bonus adds +3 decibels: changing your odds from 50% to 66% if you started out with a middling chance, but only increasing it from 90% to 95% if you're already very skilled.
(And now, back to sleep, and to see how much karma I've lost come the morning...)