Halo 2 Easter Egg - Halo 2 # of Skulls/Letters of Them

Get your Halo 2 CD case, turn it around, and look at the bottom right corner, see that jumble of letters? They are actually how many of those "Skulls" there is in the game. Here are the letters:
EGATFIBGBCSIMAW
15 'Skulls' each of these skulls give you or your enemies a speical power of some kind (As stated in another post on this site)