Quote from www.saltworks.us:
Preventing food from sticking - Rub a pancake griddle with a small bag of salt to prevent sticking and smoking. Sprinkle a little salt in the skillet before frying fish to prevent the fish from sticking. Sprinkle salt on washed skillets, waffle iron plates or griddles, heat in a warm oven, dust off salt; when they are next used, foods will not stick.
I've heard this more than once but never tried this, because I simply can't imagine why or how this works, and mostly the descriptions are a bit vague (for example, what temperature should a "warm oven" be?).
If it does work, how long does the effect last, just the next time it's used? And would there be remains of salt left in the pan when it's used next, so that one should use salt with caution after applying this procedure?