This one's a lot simpler than previous entries. The program illustrated below, gnome-volume-control, is the standalone volume control application for GNOME. The other volume control is an applet with a single slider, so this is the only way to change anything other than overall volume. Who in their right mind would let this go out the door without going "Hey, maybe the interface needs a bit of work"?
The things I use regularly are "Master", "PCM", and "CD". The things which I have no idea what they do are "Master Mono", "3D Control - Center", "3D Control - Depth", "3D Control - Switch" (and what a great UI that switch is), "Phone", "IEC958", "IEC958 Playback AC97-SPSA", "Capture", and "External Amplifier". I especially like how I get two each of the 3D controls, even though the other mixer on the system only shows one each.
There is no way to tell it to not show some of those devices, and it displays them in the order the sound card reports them.
I have to tell the single-slider volume control to control "PCM", not "Master", because if I tell it to control "Master", then muting the master channel also mutes the headphone channel, but unmuting the master channel leaves the headphone channel muted.
The "IEC958" sliders have three discrete positions. You can't get CD audio unless they're in one of the top two positions regardless of the position of the "CD" slider. There is no PC speaker noise regardless of the position of that slider.
More practical question: Is there a better GUI ALSA mixer available?
edit: Aha, "gnome-alsamixer" is better: single volume sliders and balance controls, all the sliderless switches grouped at the bottom, one tab per sound device (did you know I had two sound devices' worth of controls? I didn't!) and every control can be hidden and relabeled in preferences.
edit edit: No, nevermind, gnome-alsamixer doesn't save its hide/relabel settings. What?
edit edit edit: Nevermind that, it's a plain old bug, fixed with the patch available here. Works great now. Here's what it looks like: