I want to request or get redirected if such a plugins/extension exists to foobar.
That is when someone other than me is talking on ventrilo, foobar would automatically decrease the volume, when speech is ended there would be a fade time before it regain the volume again, incase of a fast response so it doesnt become jitterish.

I see that teamspeak with winamp got that functions and so wishes to have it with foobar and ventrilo.
I can guarantee that there are more ppl than me that are looking for exactly this type of plugin too, it would make life so much more loveable when playing EVE and having foobar rock my universe while smacktalking to my buddies on ventrilo

Ofc this would not be bound to EVE, doh !

You can do this in the wonderful kX Project driver
You place an APS Compressor+ which takes the input and alter the output.
I use it and it's very good.

If you have a Sound Blaster card(not X-Fi), give it a try.

Download here: http://www.driverheaven.net/showthread.php?t=128197

A small tutorial: http://www.driverheaven.net/showthread.php?t=122174