There's also jsDump if you don't need/want a fancy GUI:

http://flesler.blogspot.com/2008/05/jsdump-pretty-dump-of-an...

I've been using obj.toSource() until now but this will definitely come in handy https://developer.mozilla.org/en/Core_JavaScript_1.5_Referen...

If you are interested in this you may also want to check out

Blackbird visual console:: http://www.gscottolson.com/blackbirdjs/

a simple way to log messages in JavaScript and an attractive console to view and filter them

So, you know how when you point Firefox at an XML file it automatically displays styled XML? Can somebody please write an extension that does that for JSON?

Nice! Thanks for this

I think Firebug (and Firebug Lite for IE, Safari and Opera) are far better tools than this looks to be.