The following list is from our complementary monthly 'Security Chronicles' publicaton available to enterprise customers.
And not free, but well worth knowing about is our enterprise anti-malware solution that is managed through System Center Configuration Manager. Many customers have recently gained access to this as it is now part of our Core CAL license.
Be safe out there!
Nice compilation, fee free to add those on our TechNet Wiki article for Security Tools:
I would also include the Enhanced Mitigation Experience Toolkit (EMET). A free tool that helps protect applications running on a system against Zero-Day exploits.
Excellent blog post. A great collection of tools.