The Alesis airFX ($249) is what you get when you cross a theremin with a multi-effects unit. As you move your hand over the unit's infrared beam, the airFX senses its 3-D position, allowing you to simultaneously control in real time up to five parameters for any of the 50 preset effects. The presets include a variety of filtering, panning, flanging, and pitch-shifting effects. The airFX uses RCA connectors, so it can be used with stereo systems, turntables, CD players, and just about any other audio device.