If you're like most people, you don't really have a sense of what those little sliders in an equalizer do, except for the fact that the ones to the left are the ones you crank up to make things on your shelves shake. Methodshop has a great overview of how to tweak the equalizer settings in iTunes (or, by extension, any standard EQ) to get the sound you want. The examples provided make the overview extremely useful:

8K: This is getting into the high end, where the majority of cymbals and hi-hats are, as well as upper range of synths, pianos and guitars. Many vocals have a lot of information in this range.

This knowledge isn't going to turn you into an audio engineer or producer, but it'll probably make your audio sound better than it does now.

[via Lifehacker]