APSW Instant Converter
If you've ever had trouble converting units, or don't know how to turn on a calculator, this is an invaluable tool. A universal conversion program that provides conversion for heat, length, area, weight, volume, time, angular, timezones, power, energy, SI units and Avoirdupois weight and much more. It even comes with a breeding chart most useful for animal husbandry. A very simple, intuitive, useful and nice unit conversion program.