http://www.insecure.org/tools.html - - InternetScanner
Tool from Internet Security Systems, provides automated vulnerability assessment for measuring online security risks. Performs scheduled and selective probes of network services, servers, desktops, operating systems, routers, firewalls, etc. to uncover and report systems vulnerabilities that might be open to attack. Provides flexible risk management reports, prepares remediation advice, trend analyses and comprehensive data sets to support policy enforcement. Similar managed service also available.

http://www.cerias.purdue.edu/ - http://www.networkassociates.com/us/products/home.htm - http://www.mcafee.com/us/ - - NetIQ Security Analyzer
Multi-platform vulnerability scanning and assessment product. Systems are analyzed on demand or at scheduled intervals. Automatic update service allows updating with latest security tests. Includes a Software Developer's Kit to allow custom security test additions. For Windows/Solaris/Linux.