Unit Converter Pro for WP7 is an easy and useful app. The app is used to convert most useful units in the world in 17 categories which includes angle, area, currency, data storage, energy, force, fuel, length, mass, power, pressure, SI prefixes, speed, temperature, time, typography, and volume.
The currency rates are updated everyday based on data from European Central Bank. The app features an integrated calculator and is is fully compatible with dark and light themes. [via windowsphonereivew]