Based on the idea of the application 'macVerter', this little applet converts automatically between metric and US units as you type. It should be simple to add conversions, since only a minimal amount of data is required.
Open source project that offer summary and download services on this page is a project that carry out their development work on other open source development sites. Their work is linked to this page via a feature called OFI, and their work is not carried out here on OSDN site.