There was a great free unit converter for the palm OS that I used to use called "Unit Converter Pro" Not as easily accessible from the desktop, but it includes an extremely wide variety of measurement types, from magnetic induction to radiation to calorific value. I have it installed and running under GarnetVM. It is still available for free download--a Google search ought to turn it up (I don't remember the exact site where I got it just a month or two ago.)