Castor oil!! Not only is it good for growing amazing long lashes and eyebrows..but amazing for cracked, dry feet and corns! You can get it from a health food store or a high end store such as "Whole Foods".
Apply 1-2 a day.... I love applying it after a shower and before bed. You can wear cotton socks overnight for extra effectiveness.
If you have extremely dry feet, apply a mashed banana mixed with a little honey on the dry areas, let it sit for 10 minutes and then rinse. Then use a pumice stone to remove any leftover dead skin then apply castor oil.