SecLog
Seclog is a very simple but powerfull php class to protect your login form against online brute force attack at the script level. This can be combined with captcha, limited login attempts, user ban, and others techniques without conflicts. How does it protect users against attacks? It protects your authentication code so that computers never reaches it because they are fast, and only users using their real information to login will have access to the authentication code because they are slow.