What is the best [free] unit conversion software for a Windows Mobile phone?

I'm looking for a unit conversion application (e.g. grams to ounces, kilometres to miles, etc.), preferably freeware or open-source, for a phone running Windows Mobile 6. I am using an HTC Touch, so a clean, finger-friendly interface would be preferred. There are many freeware unit conversion apps for WinMo phones out there, but all of the ones I've found have clunky, tiny interfaces that necessitate getting out the stylus, or fumbling inside several menus. Where can I find a simple, nice-looking and user-friendly unit conversion application for my Windows Mobile phone?