I just created a repository on github.
For a while I've been writing a json parser (fully RFC-4627 compliant) similar in interface to rapidxml as a fun way to write some simple code that ended up being fairly complex. I mean, there's a good bit of template partial specialization in there, exception/non-exception handling, Unicode support, unit-testing, etc.
It even figures out if you've given it UTF-8, UTF-16 or UTF-32 and whether the endianness matches your machine or not.
Yeah, so that's how I have fun. Enjoy, universe!