If you own a laptop, you probably use the Volume key shortcuts (F4 and F5) to adjust your volume, rather than visiting the System Preferences or Volume menu item. Every time you press the Volume key, a full block of volume is raised or lowered in the Volume bezel on your screen. If the amount it is raised or lowered is too much or not enough, you can adjust the amount by a quarter of a block at a time. 
To fine-tune the Volume adjustment, hold the Shift and Option keys while hitting F4 or F5. This fine-tuning can be done with the Volume menu item as well, but it’s just easier to use the keyboard shortcuts. Update: This trick, as stated in the first sentence, is for Apple Laptops. While it may work with Apple desktop keyboards (I don’t have one hooked up right now, so I can’t check), it also may not work with any other branded keyboard. It’s also a Leopard-only trick.
