Magnify Dock Icons on the Fly in OS X
Even if you have Dock icon magnification turned off, you can still force Dock icons to magnify on the fly by holding down Shift-Control as you hover over apps and other icons contained in the Dock on a Mac.
Try it out yourself by moving your cursor down into the OS X Dock and moving the mouse around as normal. By default, it will do nothing, but with the Shift+Control key combo held down, the app icons will zoom as the mouse is hovered.
This key combination essentially overrides whatever is set in the broader Dock preferences, and if you have magnification turned on, it will do the opposite instead by temporarily disabling the zoom effect.