If you like organ recordings, the Reference Recordings "Felix Hell-Organ Sensation" CD will give you every octave, including notes in the 32 foot stops (20hz range). There are a lot of organ recordings with deep bass, check the archives for one from last fall on the subject. Other than some recordings with synthesizers, you'll rarely get a pop recording that gets that low, although there's plenty of recordings with bass in the 30+hz range, which many consider to be deep bass as well.
