Ok, this may be a stupid question, but....
The other day I noticed something.. I've got a pretty rough idle..which causes my alternator output to fluctuate, between 13 and 14 at warm engine idle. I noticed the other day that as the alternator output fluctuated, just slightly, my headlights followed the same pattern. The alternator needle didn't move much, but fluctuated enough that my headlights got brighter and dimmed rapidly at the same speed as the alternator needle moved.. Not only was it the headlights, but every light in the car, from the overhead light to the instrument cluster flickered with it. Now, this seems normal to me that if the alternator output fluctuated, every accessory in the car would follow that..but on the otherhand, it just seems to me like there would be some sort of safeguard or something against this...? Maybe I'm just crazy.

were you listening to your stereo?

If yours is like mine, with a good bit off bass, all of the lights slightly dim/flicker because of the electricity being used by the stereo.

Yeah, the stereo was on but volume was either at 0 or very low..I think 0. I only have a CD player and 4 factory-size speakers..no subwoofers or anything.