Using same password for different sites may raise security concern because if anyone could manage to get password of one of your account, he probably broke down into all your accounts. But beside this fact, users choose only one password for all the sites ( which includes social media sites, mailing sites and other important sites).
No one bother to use different passwords for different sites because our mind is not able to remember different passwords for different sites at the same time. There are several tools to remember our passwords. Some nice extensions are Xmarks (for Firefox, Chrome, Safari, Opera) and Lastpass. But using these extensions is not that much easy.
Punchcast is a site dedicated to solve password related problems of users. All you have to do is go to the site, enter a master password and click on the “Generate” button. The tool will generate different passwords for different sites. Now you can use these passwords for various services (you need to change the current passwords to these passwords) and set your browser to remind all those.
The only password you should remember is the master password because this is the key of rest of your password. The advantage of using this site is if you forget any of the password then enter the master password in the box again and click the “Generate” button. The site will generate the same passwords which it generated earlier.
The site includes many social networking and other important sites such as Gmail, Hotmail, WordPress, Twitter, Facebook, Paypal, Yahoo, Flickr, Amazon, etc. (hope developers would add more sites in the future).
Check out Punchcast Password Generator to use different passwords for different sites.