EqualizerEverywhere is a recently released jailbreak tweak that makes it possible to create and activate custom equalizer presets on the fly. If you're someone who listens to a variety of different audio types on the iPhone, and you're looking for a way to customize sound based on the type of audio, this is a tweak that you should definitely investigate.
We've taken EqualizerEverywhere for a spin, and we were pretty impressed by what we found. Have a look at our video walkthrough after the jump.