Rapid7's neXpose

Rapid7's neXpose
http://www.rapid7.com/vulnerability-scanner.jsp

You can download the Community Edition of this famous and highly efficient Network Vulnerability Scanner by Rapid7.

[] NeXpose Community Edition provides users with:
 > vulnerability scanning for up to 32 IPs at a time
   {limited, but for free it's nice}
 > Regular vulnerability updates
   {everytime I start it, updates get checked}
 > Accurate scan results
   {it gives real detailed analysis of flaws found}
 > Prioritized risk assessment
   {though its priorities don't match mine most of times}
 > Remediation guidance
   {yeah it's good, with required tweaks}
 > Out-of-the box Metasploit integration
   {from the Metasploit v3.31 it can be fully integrated with NeXpose}
    Link: http://www.metasploit.com/redmine/projects/framework/wiki/NeXpose_Plugin
 > Extensive community support at http://community.rapid7.com
   {it's so easy, you wouldn't require it}
 > Simple deployment
   {if you can browse through a new website, you can use it}
 > No cost start-up security solution
   {Community edition afterall}