Have to admit, I've used JSON a shit load over the past few years.
It is a lot a lot better than XML for storing data, its purely what i use it for trivial kind of settings etc, PHP and XML i really hate with the whole DOM document, i understand it is powerful n' all but its a fucking mess.
Where as doing my own library to manage JSON for simple storage solutions is a lot better.
I am trying to use it at the moment to make minimal database calls, aka heavy caching for some basic data.
Reason i got into JSON was javascript (massive fan of JS now done my own library worked with jquery) thats all based around JSON objects, where it is the only way really of managing javascript libraries.