Some of the most interesting and fun RPG mechanics come when you disregard the typical success/failure dichotomy in most games. At an extreme, "success" simply confirms what the player just stated while "Failure" denies that contribution and brings you back to square one.
So here's another idea: Instead of "Success," you get thanks. Instead of "Failure," you get complaints. This assumes whatever you said happens happens, but what follows is up to fate.
"I thwack the dragon with my broadsword!"
"You get several complaints!"
"I stab the kobold!"
"It thanks you profusely!"
Any ideas on how you'd use a system like this? Share them in the comments!