A sound engine, either as part of Anim8or or an external utility along the lines of Terranimator, would be very handy. To be able to apply a sound (sourced online, synthesized, recorded etc.) to an object and have the active camera behave like a stereo microphone would be amazing, especially if doppler shift and volume could be synthesized automatically based on relative velocity and proximity to the camera/mic. Ideally it would need to include some sound manipulation tools (and/or a full blown soft synth).
I had wild ideas of building something like this when I first found Anim8or, but have lacked the time and the requisite skills to get anything going.
PS: Congrats on completing the re-write