visual.XYT
A real-time visualization tool that extends the traditional XY oscilloscope into a third dimension: time. This allows for an intuitive observation of spatial sound characteristics emerging from the differences between the left and right channels (or, in fact, the phase of any two signals).

Try playing slightly detuned harmonics in each channel to reveal slowly evolving Lissajous figures. Observe the stereo imaging in high-quality acoustic recordings, or explore the spatial characteristics of your favorite reverb/spatializer plugin. Experiment with frequency modulation, impulse-like envelopes, and resonators to uncover new sonic shapes.