Great Firefox Utility

I have numerous uses for this great Mozilla Firefox browser plugin that I found. It splits your browser so that for example you can be answering comments in one half of your browser while reading them in the other half. There are numerous other things I do that are made much easier by splitting the screen. I do a lot of referencing and writing. This makes it much easier than constantly switching between tabs. I love it! You can download it for free here.
This is just a fantastic utility and I bet students would find it especially useful.