After reading all these raves I ran out to buy a PedEgg and it works wonders! I've had hard skin on the side of my big toe since I was a preteen
and finally it's gone!
Note to new users though: make sure you use it with the file facing up or to the side, not facing downward. I always say leave it to me to botch something easy
but I got on a roll with it, with the filing side facing down, and instead of the egg holding all the shavings they wound up all over the floor!