CMDBuild - CMDBuild is a web enterprise environment designed for asset and database management. It's a favorite among enterprises that need an advanced and secure organization solution for a great deal of files and applications... read more.
Nmap - Nmap Free Security Scanner, Port Scanner, & Network Exploration Tool. Download open source software for Linux, Windows, UNIX, FreeBSD, etc.
i-doit - i-doit is a web based Open Source IT documentation and CMDB (Configuration Management Database).
Angry IP Scanner - Open-source and cross-platform network scanner designed to be fast and simple to use
DATAGERRY - OpenSource CMDB & Asset Management, which completely leaves the definition of a data model to the user
Advanced IP Scanner - Advanced IP Scanner shows all network devices, gives you access to shared folders, and can even remotely switch computers off. Download it Free.