[S_A_P]

Pipe organ music can commonly reach down to 16 hz or so, but for those looking for (slightly) more current music containing truly deep bass here are a few options:

Pink Floyd- Dark Side of the moon. The Heartbeat in the introduction contains significant energy in the 20-40hz range

Bass Mekanik- Each of his releases includes some music but also features a test section which will play frequencies with labels as to their frequency. Even if this sort of music isnt your thing it is helpful if you are curious as to what the frequency response of your stereo.

Tchaikovsky 1812 overture- Cannon Blasts go sub sonic.

[sk5t]

Of similar vintage to Bass Mekanik, The Crystal Method's "High Roller" has some very deep, musical bass in the first minute. This bass is lost entirely by most MP3 encodings. Makes for a good reference point for both subwoofers and music sources!

[S_A_P]

Agreed. Also a really clean recording, though somewhat over squashed dynamics. But love those drums...