Here is an interesting comparison of Cortana over the course of the 4 halo games:
PTesh adds his dulcet prepubescent tones over the top of one of the new trailers for weapons...
Try upgrading your browser to Google chrome (you wont regret it). There is probably an IE...
Pillar of Autumn Bulletin Board
Level: Pillar of Autumn
There are heaps of easter eggs on this board including a reference to bungies old address, a reference to Alien (Missing: Calico Cat: Answers to Jonesy) and a poster that was used to advertise the game. The same board is found later in the game during the level "The Maw" shattered into pieces.