I just released version 0.2 (and 0.2.1, now with a NEWS file!) of JUGC, the unit conversion library generator. It allows you to specify a set of measuring units and translations in XML files and generate a conversion library from them, thus avoiding parsing a definition file at startup. The generator portion is still written in Java, but now in addition to Java, it can also generate Python code. There are small examples on the Examples wiki page. There isn't much documentation, but the example data files and tests should be clear enough.