Hmm. Outside of songs and radios, I can't think of any for World at War or Black Ops. There's a side quest in TranZit though.
Call of Duty Zombies (CODZ) is a fan-managed gaming community centered around the popular Call of Duty franchise with central focus on the Zombies mode. Created in 2009, CoDZ is the ultimate platform for discussing Zombies theories, strategies, and connecting players.