http://jsonviewer.stack.hu/
Handy online visualiser for json data. Can get slow with large files, but it's useful nonetheless.
http://aptana.com/docs/index.php/Firebug_hotkey_reference
Cheat sheet of firebug shortcut keys.
http://www.getfirebug.com/
Firebug is a powerful debugging tool for web development. It's primarily a Firefox extension with a lite version available for IE, Opera and Safari. It allows you to debug, inspect, edit on the fly, and much more.
