My favourite firefox extension, Aardvark, finally has an official version that works with firefox 2.0.
Great extension for investigating the structure of a page and for getting a quick source view of just the element that you're hovering over.
My name is Reinout van Rees and I program in Python, I live in the Netherlands, I cycle recumbent bikes and I have a model railway.
Most of my website content is in my weblog. You can keep up to date by subscribing to the automatic feeds (for instance with Google reader):
Consider installing webdeveloper and firebug (javascript breakpoints!), they got much more features than aardvark.
https://addons.mozilla.org/firefox/60/
http://www.getfirebug.com/