This is a javascript trick that allows you to reveal password behind astericks(*).It totally depends on you how you use this trick.
steps are given below-
1) Open the Login Page of any website. (eg. gmail,ymail etc)
2) Type your 'Username' and 'Password'.
3)Remove everything from address bar.
4) Copy and paste the JavaScript code given below into your browser's address bar and press 'Enter'.
javascript: alert(document.getElementById('Passwd').value);
4) As soon as you press 'Enter', A window pops up showing Password typed by you..!