I may have been the only one that didn't know this, but there is a hidden "arcade" game included with Black Ops.
At the main screen, where you choose campaign, multiplayer, zombies, etc (when your sitting in the torture chair), you tap the R1 and L1 shoulder buttons multiple times. You will then stand up out of the chair. There is a small computer terminal directly behind the chair where you were sitting. Walk around the machines on your left to get to it.
When you are close, follow the instructions to access the computer and type "DOA" (no quotes) and then select enter.
At the main screen, where you choose campaign, multiplayer, zombies, etc (when your sitting in the torture chair), you tap the R1 and L1 shoulder buttons multiple times. You will then stand up out of the chair. There is a small computer terminal directly behind the chair where you were sitting. Walk around the machines on your left to get to it.
When you are close, follow the instructions to access the computer and type "DOA" (no quotes) and then select enter.