It has a strange name, but MetaSploit is a very cool development platform that assists information security professionals in creating tools and exploits. Using the framework (its built-in tools), you can conduct penetration tests, verify patch installations and even perform regression testing. Written using Ruby, the current 3.1 version comes with over 450 modules, including 265 remote exploits that can be targeted against various releases of Windows, Linux, BSD, Unix, and the Mac OS. If that isn't enough built-in functionality for your tastes, you can also use MetaSploit to create your own modules or scour around for ones that have already been created.
Overall this is a great tool and in the hands of system administrations it can be put to good use testing your organization’s defenses. However, there are always two-sides to a shiny coin. MetaSploit is also an effective tool for conducting attacks.
I first talked about Splunk when I wrote about the 2008 RSA Conference. Yes, the Security Incident and Event Manager (SIEM) space is crowded. But Splunk is not a SIEM per se. Its approach is slightly different in that it is, like Google, primarily a search engine. As such its developers have focused much of their effort on making Splunk into a good information aggregator for IT-related information and events. So Splunk is different from other SIEMs in that it is able to provide a very good platform for correlation and analysis. From the get go, by some hidden method, Splunk takes in data and provides order where there was once chaos. In my opinion, being able to dynamically figure out different logging structures (provided you can feed Splunk data via a known basis – text primarily) is a very powerful feature which makes this tool a must-have.
Note: Splunk is not open source but you can download it for free under its developer's freeware license.