Cain & Abel
Cain & Abel is a password recovery tool for Microsoft operating systems.
It allows for easy recovery of various kinds of passwords by sniffing the network, cracking encrypted passwords using Dictionary, Brute-Force and Cryptanalysis attacks, recording VoIP conversations, decoding scrambled passwords, recovering wireless network keys, revealing password boxes, uncovering cached passwords and analyzing routing protocols.
It covers some security aspects/weakness present in protocol standards, authentication methods and caching mechanisms. Its main purpose is the simplified recovery of passwords and credentials from various sources. It also ships some "non standard" utilities for Microsoft Windows users.