PBNJ: ScanPBNJ and OutputPBNJ
The PBNJ tools are Perl scripts that use nmap to audit and a database to track changes to your network, and display change notifications.
From the website:
PBNJ is a suite of tools written in Perl. PBNJ calls Nmap to perform a scan and then PBNJ correlates the information about the targets using Nmap’s result and the PBNJ database.