Firefox Page Zoom Button

You can access Firefox's zoom function with three keyboard shortcuts Ctrl++ Ctrl+- (Ctrl+mouse wheel) and Ctrl+0 to reset to 100%.

But then there's this great tiny add-on which let's me access the browser's zoom function exactly the way I wished to:

move the mouse cursor over the icon
mouse wheel zooms
left click resets to 100%

install & more info here