Adds the input field for XPath to the bottom of each page. Beware: weekend project.

Usage: Hold Alt key and mouse click on something on the page to generate XPath. XPath is the same as generated by FireBug: id and class attributes are not used, [1] conditions are omitted. You can modify XPath and watch the selection immediately being colored in pale yellow color. Press JSON button to show prompt with JSON, containing innerHTML of selected elements.

Code is taken mostly from StackOverflow and other places over the internet, so I don't claim any rights on it. Distributed with MIT license.