The lights are on
Spoilers ahoy! Seriously, don't click here if you want to poke around and discover how to unlock the secret modes in Call of Duty: Black Ops on your own.
Controls given are for a 360 gamepad. If you can't figure out how to translate them to PS3 or PC controls, please explain your frustration in the comments section and I'm sure a measured, reasonable response that in no way impugns your skills will set you on the right path.
"Five" (Zombies map): Beat the campaign. Congrats, the better of the two Zombies maps is now unlocked!
Dead Ops Arcade: At the main menu, where you're strapped into the chair, alternate LT and RT to break free. Make your way to the old computer terminal in the corner of the room. Interact with it. At the prompt, enter "doa". Dead Ops is now available as a third option within the Zombies menu.
Zork: Get to the computer terminal like for Dead Ops, and enter "zork". Beware the darkness; you don't want to meet a Grue.
Have any more hints, tips, or secrets for Black Ops? Put 'em in the comments below!