Great addon, could use a minor change Rated 4 out of 5 stars

It works great most of the time, and does exactly what it says it does.

There are two things you could improve.

It would be great with manual website filtering (although it seems you're adding that, so that's a big plus), and there's also a strange bug where the addon just stops working after some time, and only a browser restart makes it work again. (Currently on FF beta 15.0)
I'm not sure what the cause of it is as I can't seem to notice anything unusual (or something I rarely do) when it stops working.

Edit:
Thanks for the reply!

This review is for a previous version of the add-on (2.1). 

Try 2.2beta1

The problem with ff 15.0 is fixed in TZP 2.2beta1. https://addons.mozilla.org/en-US/firefox/addon/thumbnail-zoom-plus/versions/

I plan to support manual website filtering in a future release.