I think some of you are getting very INACCURATE readings.
Not to point fingers, but there is a right and wrong way to use a decibel meter. Most decibel meters are fairly accurate. The radioshack analog meter is accurate to within 2 dB, PROVIDING FOR CORRECT PLACEMENT.
SPLs difuse, just like osmosis of water. You probably learned about that in chemistry of biology. Sound can bounce around, diffuse, and is very directional.
Measuring sound directly at the speaker grill is not going to give you an accurate reading, becuase the fact is you are simply not listening at that position! You want to measure the sound from where you would normally be located in reference to the speaker. Even then, I would be very cautious of the reading.
With headphones, I would again be very wary of the measurement, and how you take it. I think some of you have grossly inaccurate measurements, either way too loud, or too quiet.
Anyway, that said, I listen around 95dB or so, but never for extended periods of time.