Well, I did a little research about SNDVOL32.EXE and here's what I found out... 

To display the little "volume control" that shows when the speaker icon in the system tray is clicked:

NT:
DOSCommand "C:\WINNT\system32\sndvol32.exe" " "/tray" "Normal"

Win9x:
DOSCommand "[WindowsDir]\sndvol32.exe" " "/tray" "Normal"
 

The good thing about this is that the control pops up right where the mouse-click happens. It behaves like an integral part of your program!
 

Here are the parameter options:

(full size mixer)
SNDVOL32.EXE 

(small mixer)
SNDVOL32.EXE /small 

(tiny master volume)
SNDVOL32.EXE /tray 
 
 

Tip Contributed by: LASwe