Archive of exploits for many systems. Pages have not been updated since 1998 and are preserved only for posterity. http://www.insecure.org/sploits.html
A portable password cracker with built-in efficient implementations of multiple password hashing algorithms found on various Unix flavors. Additionally supports Kerberos AFS and Windows NT LanMan hashes, plus many more with contributed patches. Officially http://www.openwall.com/john/
Tool that lets a system administrator run complex or simple scanner scripts on any number of machines in a heterogeneous environment. Unmaintained since 1995. http://www.protomatter.com/rscan/
The author of Crack, a Unix password cracker. A collection of software, libraries, and documentation for Unix security. http://www.crypticide.com/users/alecm/