There is a blurb here somewhere from Dr Schulze saying that a warm bath is good for cramps but I can't find it.
He is right though. I have tried many things for cramps: white willow bark, magnesium spray, castor oil pack with heat, etc. Of course, I refuse to go back to using OTC pain relievers. Nothing works as well as a warm bath!!
Now, I slather on castor oil, take some lobelia, and get in a warm bath (not hot), then throw in some EFT for good measure.