Do you have a cool distro, tool or utility you would like to share? Reply with details at the bottom of the page and I’ll check it out.

Kali Linux (Security and Pentest distro)
http://www.kali.org/downloads/

This distro has it all except one glaring omission; Nessus. Fix this issue with my post here:
https://slice2.com/2013/04/18/installing-nessus-on-kali-linux-2/

LinuxMint
http://www.linuxmint.com/

OpenSuse
http://www.opensuse.org/en/

Debian
http://www.debian.org/

NetBSD
http://netbsd.org/releases/

Oracle
OEL (Oracle Enterprise Linux, requires free registration account)
https://edelivery.oracle.com/linux

Solaris 10
http://www.oracle.com/technetwork/server-storage/solaris10/downloads/index.html

Solaris 11
http://www.oracle.com/technetwork/server-storage/solaris11/downloads/index.html

Virtualbox
https://www.virtualbox.org/wiki/Downloads