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...
Level: Kikowani Station
At a big open location when you are in a banshee fighting AA-wraiths and blowing up spores, there is a dark section you can travel to off to the side of the map with a ramp to the left that you can climb up. If you go to the top of the ramp and then jump down to the adjacent walk-way a dancing Marty appears. Mary O'Donnell is the man behind the music in Halo and a nice little music track is played too.