I'm in the middle of an intense refactor of the Python implementation of Lingwo.ws. Its mainly based on experience I had using the Perl port at work (oh yeah, over the summer, I ported it to Perl so we could use it at work).
Since I've began this project, I've learned alot about REST and building APIs. One of the main things I've discovered is that I'm not the only one working on this. Not by a long shot.
Here are just a handful of other REST + JSON specification in the works: