At last year's MACE (a gaming convention in High Point NC) I enjoyed playing a session of Call of Cthulhu with a group of strangers. All the while I was playing, I kept thinking that all I really needed to keep me happy was a bit of a positioning mechanism. Probably one tied to a re-roll now and then.
This morning I had a little seed of an idea. Instead of spending points from a limited or semi-limited resource, there is no limit to the number of times you may re-roll your dice. But! Every time you re-roll you have to put a token in a cup that fuels the GM's resources.
I'm not sure exactly how I'd hammer down the details, but I imagine the tokens being counted & used in that standard Cthulhu third act when the horrors eventually show up. The tokens couldn't be just a straight resource, though. If the players know they're just feeding the GM's chances to kill of their characters then the choice to re-roll or not would be too straight forward.
No, those tokens would have to be seriously random and chaotic and story infulencing to be cool. Anyway, there you have it.