Rated 4 out of 5 stars

I haven't found the same functionality on any other addon, so this makes it very useful. In the meantime the original developer updates it to FF 3.5, it can be used by just editing the install.rdf file and replacing em:maxVersion tag from 3.0 to 3.5.*. It works fine under FF 3.5.2 except a minor detail: the status bar icon doesn't change to grey when it's inactive.

This review is for a previous version of the add-on (0.2c).