I didn't fully realize how much I loved this add-on and how heavily I relied on it until a glitch occurred with Google's code and I couldn't use it. (Temporarily- Michael worked with them to fix the problem as quickly as possible.) It really makes life so much simpler to have everything in one place and in one tab. I do a lot of research throughout my day, which means lots of pages open at once, but I never have to worry about opening up one for my email, another for my calendar, my reader, etc. I also love the fact that I can keep my calendar open right beneath my mail so that scheduling an event mentioned in an email becomes a breeze.
Even if you're not sure you would find this add-on useful, I recommend installing and trying it for a couple of days. I can't give you a money-back guarantee, but I'm pretty sure you're going to love how easy and useful it is. In other words- highly recommended!