EarTrumpet - Volume Control for Windows
Volume2 - Volume2 is an advanced Windows audio mixer, a complete replacement for the standard Volume Control.
Volume Icon - Volume Icon aims to be a lightweight volume control that sits in your systray.
Volumouse - From authors website:
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.