VolWheel is a little application which lets you control the sound volume easily through a tray icon you can scroll on. It is written in Perl/Gtk2 and works both for ALSA and OSS. You can configure it quickly through its configuration interface.

VolWheel is distributed under the GPLv3.

VolWheel is on the right. When you put your mouse on it, it displays the current volume level.

On left-click, VolWheel displays a MiniMixer where you can put several mixers for each channels you use the most. Useful when you don't have a mouse on your laptop.

VolWheel on Github