Proactive Password Auditor

From ElcomSoft:

Proactive Password Auditor is a password security test tool that's designed to allow Windows NT, Windows 2000 and Windows Server 2003-based systems administrators to identify and close security holes in their networks. It helps secure networks by executing an audit of account passwords, and exposing insecure account passwords. A few different methods of obtaining password hashes for further auditing are supported: from pwdump-files, Registry files, and memory of local and remote computers, including ones running Active Directory. The product features brute-force and dictionary attacks on password hashes, effectively optimized for speed (including dual-core processors), plus "rainbow" attack, that uses pre-computed hash tables that allow to find most passwords in minutes instead of days or weeks.