audiostat
X11 Popup that shows the state of your audiocontrol
...Requirement: alsa-utils
You can bind it to the audio-keys of your keyboard, As an example: I use the following keybindings in my .mwmrc:
<Key>XF86AudioLowerVolume root|window|frame|icon f.exec "amixer set 'Master' 10%- > /dev/null; audiostat"
<Key>XF86AudioRaiseVolume root|window|frame|icon f.exec "amixer set 'Master' 10%+ > /dev/null; audiostat"
<Key>XF86AudioMute root|window|frame|icon f.exec "amixer set 'Master' toggle > /dev/null; audiostat"