My first wallpaper i've ever made. It's got all of the new and old medals that appear in Halo 3. I did this because I never seem anything having to do with the medals so I thought that this would be cool. And in case you don't know some of the medals or don't know of the changes Bungie made, here are all the medal's names and descriptions corresponding to my wallpaper reading left to right:

Double Kill - 2 kills in a row, all within 4 seconds of the last kill
Triple Kill - 3 kills in a row, all within 4 seconds of the last kill
Overkill - 4 kills in a row, all within 4 seconds of the last kill
Killtacular - 5 kills in a row, all within 4 seconds of the last kill
Killtrocity - 6 kills in a row, all within 4 seconds of the last kill
Killamanjaro - 7 kills in a row, all within 4 seconds of the last kill
Killtastrophe - 8 kills in a row, all within 4 seconds of the last kill
Killapocalypse - 9 kills in a row, all within 4 seconds of the last kill
Killionaire - 10 kills in a row, all within 4 seconds of the last kill
Beat Down - Hit and kill an opponent with the melee attack
Killing Spree - Kill 5 opponents without dying
Killing Frenzy - Kill 10 opponents without dying
Running Riot - Kill 15 opponents without dying
Rampage - Kill 20 opponents without dying
Untouchable - Kill 25 opponents without dying
Invincable - Kill 30 opponents without dying
Shotgun Spree - Kill 5 opponents with the shotgun in a row without dying
Assassination - Hit and kill an opponent on the back with the melee attack
V.I.P. Kill - Kill the opposing teams V.I.P.
Flag Carrier Kill - Kill the opponent holding the flag
Laser Kill - Kill an opponent with the Spartan Laser
Bomb Carrier Kill - Kill the opponent holding the flag
Killjoy - End an opponents killing spree
Open Season - Kill 10 opponents with the shotgun in a row without dying
Sniper Kill - Kill an opponent with a sniper rifle
Sniper Spree - Kill 5 opponents with the sniper rifle in a row without dying
Sharpshooter - Kill 10 opponents with the sniper rifle in a row without dying
Wheelman - Be driving a vehicle when a passenger kills an opponent
Splatter - Kill an opponent by running them over with a vehicle
Splatter Spree - Splatter 5 opponents in a row without dying
Vehicular Manslaughter - Splatter 10 opponents in a row without dying
Hijacker - Successfully board a vehicle
Skyjacker - Successfully board a flying vehicle
Hail To The King - Kill 5 opponents in a row without dying while in the Hill
Perfection - Get 15 or more kills and never die during a game
Death From The Grave - Kill an opponent after you die and before you respawn
Bomb Planted - Plant the bomb successfully
Flag Captured - Capture the opponent's flag
Grenade Stick - Stick an opponent with the Plasma or Spike Grenade
Extermination - Get an Overkill that results with the entire opposing team being dead
Oddball Kill - Kill an opponent by meleeing them with the ball
Flag Kill - Kill an opponent by meleeing them with the flag

Edit: I just found out, very recently after posting this, that I'm missing three medals that I know of, which are:
Sword Spree
Slice And Dice
True Blue (I think that's the name)

Edit 03/03/08: Alright, people, pay attention to when I submitted this and the comments already here. I made this before Halo 3 even came out and I never played the BETA either, so shaddup about the ones I missed. I realize I missed them.