Ophcrack is a Windows password cracker based on a time-memory trade-off using rainbow tables. This is a new variant of Hellman's original trade-off with better performance. It recovers 99.9% of alphanumeric passwords in seconds.
Features
Cracks LM and NTLM Windows hashes
Free tables available for Windows XP, Vista and 7
Brute-force module for simple passwords
Source code and additional information can be found here: https://sourceforge.net/projects/ophcrack/