Firecookie http://www.softwareishard.com/blog/firecookie/
Firequery http://firequery.binaryage.com/
Firepicker http://thedarkone.github.com/firepicker/
Jsonview http://jsonview.com/
Colorzilla http://www.colorzilla.com/firefox/
Built into the Webkit Developer Tools
> Firequery http://firequery.binaryage.com/
jQuery objects visualisation (in console and inspector) are in the Developer Tools, rest is not (though the injection is a bookmarklet/browser extension away)
> Firepicker http://thedarkone.github.com/firepicker/
Missing indeed, Opera's Dragonfly has a color picker but the webkit devtools don't.
> Jsonview http://jsonview.com/
https://chrome.google.com/webstore/detail/chklaanhfefbnpoihc...
https://chrome.google.com/webstore/detail/ddngkjbldiejbheifc...
https://github.com/rfletcher/safari-json-formatter
> Colorzilla http://www.colorzilla.com/firefox/
https://chrome.google.com/webstore/detail/hmdcmlfkchdmnmnmhe... ?
On an unrelated note I can't live without tree style tabs(On average I have 30+ open tabs, which is unmanageable in chrome, hangs some time) and vimperator. All in all I still prefer firefox.