sleeping with a humidifier is AMAZING! last year before a showcase I did that and I saved my voice JUST ENOUGH to get by that night.
It's pretty bad for you.. but I know singers who (if NOTHING is working) get steroid shots. I would DEFINITELY not reccommend it as a first, scond, third, or even fourth option, but it worked with one of my best friends who was Gaston in B&B last year. :)
some things are meant to be...