a free cross platform precise unit converter, supports 6000+ units
The NumericalChameleon is a free, open source, cross platform software in order to convert units. It converts numbers with a precision of up to 1000 significant figures. It supports more than 6000 units in 94 categories. It has been localized in 10 languages.
GpsPrune is a java application to view and manage coordinate data, eg from GPS units. With it you can load a variety of text and Xml formats, view the data (in 2d and 3d), edit and convert the data, correlate photos and audio, create charts and more.