Humidity sensors as part of engine control

Can anyone tell me if humidity sensors were or are being used in automobiles or any engines? Also, what benefits would be gained from using such a sensor and would it be worth the trouble to implement it? Thanks.

i have never seen or heard of one before, but they have a sensor for everything else basicly, maybe one day there will be.

i do know during a heavy rainstorm the air is wet enough to affect the air/fuel raito. i think the engine runs a little rich due to the water taking place of air(hence less burnible air). i don't know how much of a real affect humidity has(honistly, i'm talking from memory) maybe we will see it on OBD-8 or something