If you are not worried about someone looking from behind your back and stealing your passwords, why take additional pain for typing **** password fields, where you dont know whether you typed your long password correctly or not
The addon is seen as an image in status bar.
Clicking on the image shows all the "password" boxes in the page and shows it in text.
Clicking on the image again converts "password" fields back to "password" and hides the text written in the field.
You might want to read the following blogs for a expert's view of the problem.
Bruce Schneier: http://www.schneier.com/blog/archives/2009/06/the_problem_wit_2.html
Jakob Nielsen: http://www.useit.com/alertbox/passwords.html
Mike Andrews: http://www.mikeandrews.com/2009/06/25/no-typepassword-fields
Awarded "Famous Software Award" by Download.FamousWhy.com (http://download.famouswhy.com/show_password/)