For those of you who can ban certain passwords (such as "password" or "abc123"), you may be interested in SplashData's list of the worst passwords of 2013.
Here are the top ten jewels for your banning pleasure:
For those of you who don't have this power, you can use this list to help educate your users on what constitutes a bad password and maybe guide them into using stronger passwords. Most security firms recommend passphrases, like the estimable "correct horse battery staple". Even suggestions like "use your favorite sports team and favorite player number" are better than the tried and broken "company/product and 123".