In case you haven't downloaded it, check out The Colorzilla extension for Firefox. Not only is it a groovy color picker, but it reproduces a large chunk of what I use both the web development tool bar and dom inspector for, in one really easy step. Just go download it.

Right click on it and change your status bar to something like "%hex%|%dist%|%element%|%dom-path%" and revel in the webdevy goodness.

Mmmm

Eyedropper Gooey Web Devy Goodness.