Look into foot peels. They usually contain salicylic acid. I didn't believe that alone would do anything but I'm now a convert. The aftermath is gross for a few days, but for a brief moment in time you'll have baby smooth feet. A few tips:

• Obviously patch test to check you don't get a negative reaction
• Soak your feet in warm water for about 10 mins before
• Keep the foot peel socks on longer than it says on the packaging (if it says 60 mins, keep them on 90 min)
• Put socks over the foot peel socks so the liquid reaches all the nooks and crannies.
• Get comfortable and watch a movie or something while you wait
• In the days following, soak your feet once a day for 5-10 mins. This speeds up the peeling time.
• Wear socks and when you take them off, turn them inside out above a trash can.
• Resist the urge to peel the skin off. This is the hardest step
• Final step is to enjoy your smooth feet and look into repeating in a few months, especially if you have some very stubborn areas.