A password strength calculator. I've attempted to correct one flaw I've seen in most password strength calculators. That is they don't take into account dictionary attacks. For example the password 'password1' might get a decent score as it's nine characters and contains a number. However, it is one of the most common passwords used, so it would fail very fast to a dictionary attack. I've only included a small dictionary of the most common english words and passwords. It doesn't try any of the common variations that an actual attacker would (e.g. 0 for o).
See here. I wrote something about passwords on my blog.