It turns out that a few fans have been combing through the Halo 3 Beta source codes looking for any new hidden features. They stumbled on this little bit of code. New customizable items like the Spartan Cobra Helmet, Spartan Intruder Helmet, Spartan Ninja Helmet, and the Spartan Regulator Helmet are sure to make any Halo fan even more eager to beat down their friends in style. Source