And no mention of the Nazi Zombies soundtrack would ever be complete with the song that started them all off, the fantastic Lullaby for a Dead Man.
And the old school "Taking Stalingrad" from the first game. Badass epic song, coping with screens from Enemy at the Gates and you as Vasiliy Zaitsev's twin brother, taking on the German machine-guns with just some ammo bullets. WaW and MW2 are probably some of the best games in history but nothing beats the good old fashioned COD1.
MW3's soundtrack, courtesy of Brian Tyler (of Transformers Prime fame), has some excellent tracks as well. "Russian Deliberations" lends an awesome sense of gravitas to the Russian President's entrance, while the Main Theme carries an epic feeling of finality, fitting for the end of the trilogy.
Arabian Endgame, the music for the final level, is pure epic in musical form.
Also, the zombie soundtrack is especially nice. , the main theme, does a good job of setting the mood for your 30 minute zombie killing marathon. And who hasn't gone to the extra trouble of picking every meteorite fragment to hear this while blasting zombies? 
The Kowloon level "Numbers" had this as good background music, especially from 8:17 onwards.
There's a certain campaign mission where you pilot a boat down a Vietnamese river at night, shooting a combination of rockets and gunfire at the Vietcong on the shoreline. Treyarch could've just put in orchestral music in the background to reflect the action of the level, but what do they play instead? The freaking Rolling Stones.
And Eminem (yes, Eminem!) feat. Pink with "Won't Back Down". A-mazing and awesome.
Jack Wall truly outdoes himself with Black Ops II's soundtrack. In the very first mission, your ears are greeted with the epic brass and percussion of "Savimbi's Pride", and the game just keeps coming at you with equally awesome tracks from there. Standouts include "Suicide Ride" (from "Old Wounds"), the "theme of Raul Menendez", "Dockside" (from the end of "Karma"), "Dogfight" (from the F/A-38 sequence in "Cordis Die"), and the epic finisher that is "Hero's Theme" (played as Menendez is carted off to jail at the very end of the campaign). And of course, the main theme, composed by Trent Reznor, is exceptional as well, doing a great job of setting the mood for a bleak, violent future war.
The first game's intro song, which itself is remixed from a Immediate Music song. It pretty much fits the atmosphere of the first game.