Hi,
I have recently created a set of Halo icons For Mac OS X. You can veiw and download them from http://www.eddav.dyndns.org/halo2_icons/index.html . There are also .jpeg, .psd and .ico resources you can download.
The Halo 2 Icon set consists of 38 128x128 high-res Icons of various characters, weapons and vehicles from the game. There are even some vehicles (such as the warthog variations) which I included, that are not on the final game.
I hope you enjoy them!
Eddav