I was asked by a client on how to tell if someone’s password was strong enough. I was not sure on the need, and at first I was looking to either build or find a webservice that would test strength. After hearing the need over the phone we were able to use some already build applications (web sites) to do what they were looking for.
http://www.microsoft.com/protect/yourself/password/checker.mspx
http://www.securitystats.com/tools/password.php