Dropbox - Password strength is indicated by colored bars underneath the input field. /via rammionline
Using the Included Password Strength Meter Script in WordPress - Tuts+ Code Article
GoCardless Password Strength-O-Meter (gif)
Password Meters' Impact on Password Strength
How to Craft Effective Registration
Password-Strength is a jQuery based password strength checker and indicator that helps users meet your minimum password requirements.
From xkcd and Lifehacker: How to create passwords that are both easy for you to remember and hard for computers to hack
The thing is, your password strength is only as hard to crack as it is for you to remember. The harder it is to remember, the harder it will be to crack. It’s as simple as that.
How Your Passwords Are Stored on the Internet (and When Your Password Strength Doesn't Matter) -- LifeHacker, June 20, 2012
8 Best jQuery Password/Strength Meter Plugins | SmashingApps.com