Half-Life 2 Xbox Cheats

Spawn Medpak:

 Press Up, Up, Down, Down, Left, Right, Left, Right, B, A during game play to spawn a medpak that restores 25 health points. 
Restore Ammunition:

 Press Y, B, A, X, White, Y, X, A, B, White during gameplay to restore your current weapon's ammunition.  
Unlock all chapters:

 Press Left, Left, Left, Left, Black, Right, Right, Right, Right, White during gameplay to unlock all the chapters. 
Headcrabs roasting on a open fire:

 After you blow up the chopper, make for the gate.  Inside there, use the boat as a booster to jump into the higher tunnel.  Inside it, you'll see a pool of nuclear waste.  Swim to the other side of it, and head down the tunnel on the left.  You'll find a alien slave cooking headcrabs on a stick!  Not too useful, but funny.
Easy Queen Antlion kill

Take a crossbow and aim at the middle of the antlion queen and shoot about 4 times and it should come crashing down 




 Thanks to Revolution readers Seth, One_of_Them, and nick!