Finding the perfect spot, whether you’re just trying to adjust your pillow at night or trying to set the volume on your Mac, is tedious, to say the least. The latter was made all the more difficult when OS X 10.7 took away the ability to increase or decrease the volume by one-fourth of a volume block. The precision was dearly missed particularly by musicphiles and generally by all users. Just as the option disappeared magically, it has returned the same way (it might have something to do with the OS X 10.7.4 update, but magic sounds cooler). You can now increase the volume bit by bit once again. Hold down the Shift+Option key combination when using the volume keys on your keyboard, and the volume will increase or decrease ever so slightly until it is just right.
Remember that you must hold down both the Shift and Option keys. If you think the Option key is meant only to be used if you have disabled the default function keys, think again. The slight problem that seems to emerge with the return of this feature is that you can no longer disable the default action of the volume function keys using FunctionFlip (as covered here), and continue to use the volume key holding down Option. If your keyboard has a separate Fn and Option key, all doors are still open. If not, it’s time to chose what you really want your Function keys to do.
Overall, most Mac users will be happy this option is back. Volume is rather a touchy item to mess around with, and anything that makes it easier, is always welcome.