Just for windows phone a new user friendly App that makes unit conversions very easy,
It contains the most important imperial and metric conversion factors for length, area, volume, angle, temperature, sound, weight. For example Angle: (Degrees MMss, Degrees Decimal, Gradian, Radian), Temperature: (Celsius, Kelvin, Fahrenheit, Rankine, Reaumur), etc. Its easy to use, for example you may convert decimal degrees to degrees minutes and seconds, grads, and rads with a simple tap on the screen. It also provides many high-specialized units and categories, too, such as Slope/grade, Flow: (m3/s, m3/min, m3/h, liter/s, liter/min, liter/h), and Roman numerals.