Popular Wi-Fi password cracking tool Backtrack
The Kali distribution includes Metasploit, Wireshark, John the Ripper, Nmap, Aircrack-ng, and others to provide a security testing suite you can easily boot up from a Live CD. The distribution comes in not only 32- and 64-bit flavors, but also works with ARM-based systems as well. That means Kali can run on some Chromebooks and even the Raspberry Pi. Check out the Kali site for the official downloads and more information.