fade in/out music/tracks would be great 
My sound guy wants to do stereo stuff for example where a sound would have a source and it would change depending on the player position as he moves through the scene. Yes random overlay tracks over main soundtrack with if true. Also more tracks for smaller sound effects triggered or randomly occuring. More tools for that kind of stuff would be great even if it's LUA.
Kind of possible already with Lua & openAL sound engine. Check out the sound functions under
Player Commands of the scripting section of the wiki.
Determing the balance of sounds requires that you calculate the distance of the character from each sound source position & whether it is negative or positive value - would probably require loops & tables if you want to update sound balance in real time of all active sounds while character is walking around. Alternatively the simpler solution is to base it on the center of the current camera position instead.
It is possible to dynamically offset though as I wrote a script a couple years back for Thomas & Zak 2 - don't know if he ended up using the script, but long story short... it was for dynamically playing footstep sounds based on character position on scene as well as selecting a random footstep sound from a Lua table based on the current terrain type. It also as far as I remember generated a random volume level to play each new footstep at to make it appear the character was treading light or heavy at times - you know to mix things up a bit.
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