In a nutshell, the idea is a config on/off button that you can toggle that allows pre-set ambient soundtracks to play through the MOO based on the Sector/room you're in. A specific example I was thinking of was the levs. Someone could get a sound byte of a subway station (or just get one online) as the train slides in and when the lev arrives the message of the train arriving triggers the sound byte so you get to hear the lev pull in through your speakers.
It could go as far as having ambient soundtracks in Red/Gold/Green, as well as maybe specific ambients for clubs and factories and the like.
Only downside is I imagine this has the potential of drastically increasing server costs as we would be pushing sound files instead of just text, but I'm no expert in that world.