List of some free Programs.

Amazingly enough, almost anything you can do using commercial software, you can do it using free software but the problem is how to locate these programs when needed?! yeah how?
There are plenty of sites that keep lists of best 100 or more or less programs (http://sectools.org) . I like these lists! and I thought, well, why not make one of my own?!

and here it is free of charge!

WhireShark at http://www.wireshark.org.
Ettercap at http://ettercap.sourceforge.net.
Nmap at http://insecure.org.
Ncat at http://www.vulnwatch.org/netcat.
Cain & Abel at http://www.oxid.it.
Metasploit at http://www.metasploit.com.
Vmware Server at http://www.vmware.com.
Microsoft Virtual Server at http://www.microsoft.com/windowsserversystem/virtualserver.
Vyatta at http://www.vyatta.com.
Firefox + Firebug respectively at http://www.mozilla.com and http://www.getfirebug.com.
OllyDBG at http://www.ollydbg.de.
Visual studio 2008 express edition at http://www.microsoft.com/express/download.

[This list will be updated when I'll discover interesting tools! ]