How Secure is my Password?
HowSecureIsMyPassword.net is a site for checking the strength of passwords in a simple and fun way. The strength is not shown in the conventional progress bar, but in very descriptive sentences.
For example if you enter asdf you'll get "Your password is one of the 500 most common passwords. It would be cracked almost instantly" and 1234567890 will show "It would take about 16 minutes for a desktop PC to crack your password".
The developer of the site, Small Hadron Collider, provides the JavaScript source code and a jQuery plugin for download if you would like to use it on your website.