The Carpet Bomber was a Call of Duty: World at War killstreak that was taken out during the final stages of development in the game. Browsing through the game's audio files, you can listen to the multiplayer announcers say things such as "Carpet Bomber ready!"
It was to be the equivalent of Call of Duty 4: Modern Warfare's Airstrike, and was replaced with a simpler Artillery Strike in the final version.
Function
The Carpet Bomber was to be either a P-51 Mustang (Marine Raiders), Mitsubishi Zero (Imperial Army), MiG-3 (Red Army) or a Messerschmitt ME109 (Wehrmacht). The plane(s) would drop multiple bombs onto a stretch of land, wiping out enemies within the radius.