Looks like Call of Duty: Black Ops has some hidden surprises for the players in the main menu screen, the one where you're trapped in a room. Basically if you can not find a way to escape from the chair two surprises will be there waiting for you. Behind the seat there is a computer that allows Mac style of writing.

When you unlock the keyboard and write DOA Dead Ops mode, which can be accessed from the main menu. This mode will be playable in single or co-op and will contain the achievements, the best surprise, however, is when you write ZORK the computer that you will, of course, to release Zork. Here we leave you the video that explains how to unlock these surprises.

Call of Duty: Black Ops - Trailer