EarTrumpet - Volume Control for Windows
Volume2 - Volume2 is an advanced Windows audio mixer, a complete replacement for the standard Volume Control.
Volwheel - VolWheel is a little application which lets you control the sound volume easily through a tray icon...
Volti - Volti is an GTK+ application for controlling audio volume from system tray/notification area.
KMix - KMix is an application to allow you to change the volume of your sound card.
Volumouse - From authors website: