My brother and I (a.k.a. OMG Audio) have finally finished the commercial release of our audio visualization / analysis tool, Incoherence. (Scroll down on that page for free plug-ins.) The idea is to display a picture of the stereo image of your mix, broken out by frequency. After talking to some producers and engineers, we realized that a lot of people are imagining something like this while they work, and we figured, why not make a tool so they can see what they're doing?
Your comments would be greatly appreciated. Do you think this is something people would find useful?