For starters, here's what I'd like to see implemented, feel free to modify or make your own sample.
-Master Volume (Raises and lowers the multiplier for all volume)
-Menu Volume (the crisp 'boom' as you select options on the menu, and any other menu sounds)
-Weapon Volume
-Silly voice volume (Round starts/ends/death/siege)
-Environment Volume (Grunting/jumping, footsteps, map sound effects such as water, or 'Weee' in bombsaway.)
Although, adjusting volume for footsteps seems a little sketchy.