What's a simple, cheap treatment for my calluses and corns?

Many: If you are healthy, there are over the counter treatments that are safe such as pads designed to thin the problem area and devices to thin the skin (pumice stone, etc.). It is best to use in or immediately after showering. Often, visits to the doctor every 3-6 mo. Will take away the pain by shaving the areas down (it doesnt hurt).

Simple: Soak in warm soapy water and then use a pumice stone to scrape them down and then apply a good lotion.