The Unit Converter is an Android app that converts miles and kilometers, grams and pounds, and Fahrenheit and Celsius. This project was assigned as a school project at UC Berkeley for User Interfaces (CS160).
I ran this application through Eclipse and the Android SDK, so if you want to try that, follow the directions here: http://teaching.paulos.net/cs160/index.php/Section_1:_Installing_the_Android_SDK