The RegLookup project is devoted to direct analysis of Windows NT-based registry files. RegLookup provides command line tools, a C API, and a Python module for accessing registry data structures. The project has a focus on providing tools for digital forensic examiners (though it is useful for many purposes), and includes algorithms for retrieving deleted data structures from registry hives.
Lynis is an auditing tool for Unix (specialists). It scans systems to detect software and security issues. Besides security-related information, it will also scan for general system information, installed packages, and possible configuration mistakes. The software is aimed at assisting automated auditing, software patch management, and vulnerability and malware scanning of Unix-based systems.