What Janet said for starters...
Time and Nu-Skin will help for starters and I am a strong advocate for wearing something...anything on the mat ( I just use a set of very thick socks but I've paid very close attention to Janet Rosen's experiment with the vibram toe shoes)...especially until your feet heal. MRSA is no joke.
My feet spent years in combat boots carrying 80 to 100 pound loads so in my opinion calluses are much better than blisters or cracked feet. The risk of infection from antibiotic resistant bacteria is growing rapidly.