I suffered with dry skin on the heels of my feet for years, and I'd not managed to find anything that'd shift them effectively. Then I picked up one of these Ped Eggs.
If you haven't seen them, they're effectively a cheese grater for your feet. You might be cringing already, but to be honest, I've never had a problem with them. First time I used it, it took about twenty minutes, and it took 90% of the dead skin off my feet immediately, with no pain or problems. It catches all the flakes in a compartment, which is then easily emptied and cleaned.
If anything, they're a little too effective; after one use, you barely need to use it again... If you have problems with calluses on your feet, this comes highly recommended.