I had a friend in Panama that used the salt crystal deodorant for his feet. He had really bad foot odor, as attested to by his DW, and that stuff really worked. I use itfor regular deodorant (TMI, I know) because of sensitivities to chemicals in normal products (TMI, I know, again).

This is what the product looks like. I have found it a natural health food stores and some places like Walgreens/Rexall/CVS.

Usual disclaimers.

http://www.amazon.com/Crystal-Body-Deodorant-Stick-4-25-Ounces/dp/B0000AQJ9N

BTW: It lasts a long time if you don't drop it.