RSON (Readable Serial Object Notation) is a superset of JSON that is suitable for files that humans have to edit and diff.
The current release is decoder-only, but the decoder will read files encoded by JSON encoders such as json or simplejson. The current release consists of a single Python module and a short manual. The manual admittedly needs some work, but has a few syntax examples. http://code.google.com/p/rson/ -- http://mail.python.org/mailman/listinfo/python-list