harrym

WordPress uses phpass to store passwords. Because WordPress has to work everywere, it uses the portable version of phpass, 
which uses MD5 to hash passwords. MD5 is not a very good hashing algorithm for passwords, because it’s relatively fast.
This plugin switches over to bcrypt, which is the algorithm recommended by phpass, and is a much better option for password 
storage because it is much slower to produce. This makes it much harder for an attacker who’s managed to access your hashed 
passwords to obtain plain text passwords by brute-forcing, or by trying passwords from a dictionary.
Note: this plugin requires PHP 5.3.0 or newer
Be aware that if you use this plugin and then move to a host that does not support bcrypt, you will need to reset any user 
account that you want to log in with.

wp-bcrypt

wp bcrypt switches WordPress's password hashes from MD5 to bcrypt, making it harder for them to be brute-forced if they are leaked.

David Anderson / Team Updraft

This plugin forbids any user to choose any password from the “common passwords list” obtained from http://www.openwall.com/passwords/wordlists/, and requires any who are already doing so to reset their passwords.
<h3>License</h3>
Copyright 2012- David Anderson
MIT License:
Permission is hereby granted, free of charge, to any person obtaining 
a copy of this software and associated documentation files (the 
“Software”), to deal in the Software without restriction, including 
without limitation the rights to use, copy, modify, merge, publish, 
distribute, sublicense, and/or sell copies of the Software, and to 
permit persons to whom the Software is furnished to do so, subject to 
the following conditions:
The above copyright notice and this permission notice shall be 
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, 
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE 
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

No Weak Passwords

This plugin forbids any user to choose any password from the "common passwords list" obtained from http://www.openwall.

wp-bcrypt vs No Weak Passwords