On Blogstorm there’s an article that describes a simple method that allows you to edit any website live in your browser. You just have to type the following code in your address bar:
The method works in all modern browsers (Internet Explorer 6 also). The edit mode can be disabled by typing this code in the adress bar (doesn’t work in Firefox):
Of course, modern web development tools like Firebug also support this feature but for a quick change (you can simply bookmark the code line), this method is very nice I think.