Rated 5 out of 5 stars

Works great with Firefox 3.5 and Mac Os X 10.5.7! This is just what I was looking for---simple and effective. Thank you!

This review is for a previous version of the add-on (1.1.3). 

Great to hear! Um, read! :)

I had heard that there were issues with the Scroll Zoom button/option on Mac. I'm glad to see that you don't have any problems. Feel free to report any that you do come across.