A very simple extension for learning web page colors. Copy the RGB or Hex color code of any pixel displayed in your browser to the clipboard (in CSS/HTML format). Less than 40 lines of code. Similar in function to Internet Explorer’s color picker.
Here is a little more information about this add-on:
Very simple and similar in function to Internet Explorer’s color picker. Useful for finding the exact color code (RGB or Hex) of any pixel displayed on any web page. Open colorPicker from the Firefox Tools Menu (Web Developer Menu or Add-On Bar in v1.5) and then place your mouse over any pixel in the browser. The panel will display the color of the pixel currently under the mouse icon as well as both the RGB and Hex code of that color. Press escape to copy the CSS and HTML ready RGB or Hex code to your clipboard. Select either RGB or Hex code for copying via Add-Ons Options panel. There is no trust required like other complicated color tools – this one is less than 40 lines of code so you can quickly check the source!
You can pick up colorPicker at the Firefox Add-ons website.