I recommended the Soap and Glory foot file last year but have found something BETTER!
It's the Emjoi Micro Pedi. Quite pricey at £34.99 < Argos price, it's £39.99 in Boots > but really, really good!
My feet are in good condition anyway but this was really effective and got loads more skin off [ yuck, i know ]...Good quality batteries are needed - you just press the button and it does all the hard work. I'm dead impressed and it's got rave reviews.