Another company, On-Core, has released two more Dock-based applications that they call Docklings. On-Coreis two Docklings offer handy controls for system volume and audio CD playback. According to On-Core:
AudioCD Player Dockling - Ver 1.0.0: Add this dockling to your dock and play audio CDis! What could be easier?
Volume Dockling - Ver 1.0.0: Add this dockling to your dock and be able to control the system volume easily.
Both these Docklings are available as "Donationware." You can find more information at the On-Core Web site.