If you're searching for a complex conversion program for Android, what I recommend you to try is "Unit Converter". It is a fully featured Unit Converter and Calculator. As I've told you in the title, this can convert (and also calculate) almost anything. Starting from Length, Weight, Volume, Time, continuing with Surface Tension, Permeability, Fuel Efficiency - Mass, and finishing with Typography, Cooking and Lumber (and tens of others).
This application is very popular on the Market, having over 250 000 downloads currently. It is very useful especially at Physics (at school), but also when you want to convert something fast and you don't want to stay and think how it is the best to convert that. It has even a currency converter (but unfortunately it has a limited number of currencies and needs a data connection to update). But, what matters, it is free.
Download it now from the Market : "Unit Converter - Convertpad " (type full name, the application is by Sunny Moon).