MINIX 3 is a new open-source operating system designed to be highly reliable, flexible, and secure. It is loosely based somewhat on previous versions of MINIX, but is fundamentally different in many key ways.
The OpenBIOS project provides you with most free and open source Open Firmware implementations available. Here you find several implementations of IEEE 1275-1994 (Referred to as Open Firmware) compliant firmware.
Ophcrack is a Windows password cracker based on rainbow tables. It is a very efficient implementation of rainbow tables done by the inventors of the method.