Firefox should have this built-in! (esp. since zoom isn't in the fx app button but only in hidden View menu) Rated 4 out of 5 stars

I personally prefer to use NoSquint ( addons.mozilla.org/firefox/addon/nosquint/ ) because it can set *any combination* of full-page and text-only zoom in effect at the same time. But that may be more than most users need, in which case I recommend ZoomPage because it's simpler and has a more compact all-in-one toolbar button.

It's great that the button has a (customizable) zoom menu (or Reset to default) and the ability to switch to text-only zoom, and an easy way to toggle site-specific zoom memory. I tried a couple other similar add-ons but they weren't as good.

BTW, this add-on is in my collection Compact Efficient Interface Maximizes Screen Height Available for Page Content ( addons.mozilla.org/firefox/collections/dabruro/compact/ )

Add-on would be even better if:
1. Have a zoom menu but also a single-click reset. Could divide the current button into four sub-buttons instead of the current three?
2. have a visual indication of whether the zoom level is 100% and whether it's at the default (e.g. if this is set to 90%).
3. More-informative tooltips: say whether current mode is text-only or not, current mode site-specific or not, reminders of keyboard shortcuts appropriate to that sub-button such as Ctrl+-, and more understandable "zoom everything" since "full page" sounds like full-screen to non-experts.
4. is an image-only zoom option possible? Even though this is separate from fx's normal page zoom mechanism, it is the natural complement to text-only zoom from the users's point of view (they don't care that the implementation is different).

Edit after developer reply to my point 1: thanks, I didn't realize the middle-click could be used that way. I personally still would prefer another way to do both a reset and a zoom since my thinkpad strangely has no physical middle button to use with the trackpad :-)
Thanks again for a good add-on.

This review is for a previous version of the add-on (4.3). 

Middle-click zoom reset

Thanks for these suggestions. With regards to your first point, it is already possible to have the zoom menu enabled (left-click zoom reset disabled) and at the same time have a single click zoom reset (using middle-click reset). Middle-click on the percentage always resets the zoom to the default value.