Is there any software to always show the volume level? (not GeekTool)

I have been looking around for 2 hours now and getting quite exhausted. I've been messing with GeekTool with no avail. So, I figured I'd ask the Apple world to see if you guys knew of any ways to constantly show the volume level on screen while a user is using your computer.

We are using multiple computers for multi-media during an event, and don't want the deaf guy making other people deaf while using the same computer due to the unknown volume level.

Any other ideas for a solution in this situation would also be helpful. Although, I would like to mention we do not want to have a "cap" on the volume for those people that are really deaf or can't hear due to loud environmental situations.

Thanks,

itsonvia