This trivial little Safari extension does one trivial little thing: When you move the mouse over a password input field (the kind that shows asterisks in place of the actual password), the password is magically revealed. When you move the mouse out of the password field, the password is obscured again.
ShowPass only works on sites that use the standard HTML tag for password input fields. It makes no attempt to do anything with fancy-pants password fields that use some other method to obscure the password.
Please note that ShowPass does not do anything you couldn’t do using Safari’s own web inspector.