Do you have a monitor so big it makes your screen looks empty when you only have one website opened in browser? This probably happens to those that uses wide screen monitors. Firefox browser comes with a sidebar that allows you to run web applications on it. So while doing the surfing on the right side, you too can have something running on the left sidebar. It greatly increases productivity if the entire browser is fully utilized.
Here’s 20 Useful Web Applications you can place on Firefox Sidebars.