Wouldn't it be great if somebody built a USB breath controller? The midi specs are already there, and software FM synths can play all those Yamaha presets that still are configured for breath control.
I'm thinking a little plastic box with a plastic hose and fitting that you place in your mouth. A pressure transducer, USB bus powered - it would just spit out midi control data. Maybe the software driver could have a user interface for tweaking the response curve and control number and midi channel.