Cain and Abel
Cain and Abel is a password recovery tool that enables network administrators to test network security, or home users to recover a variety of stored network passwords. The program reports sniffing and recovery of most popular protocols, including FTP, SMTP, POP3, HTTP, mySQL, ICQ, Telnet and others. It can also recover passwords hidden behind asterisk (***), stored in VNC profiles, SQL Server Enterprise Manager, Remote Desktop connections and wireless connections. Other features include LSA Secrets Dumper, Protected Storage password revealer, network enumeration, VoIP filtering and more. Probably one of the most complete network password recovery/security tools you can find. Cain and Abel is intended for network administrators or advanced users.
NOTE: Expect your antivirus software to alert you of a password cracking or hacking tool when installing this software!