Rated 5 out of 5 stars
This has very quickly become by far my favourite-ever Gmail utility, and I've used Gmail since the first week it was invented. For a long time I used Gmail Manager, but it was kind of big and quirky for me. It seemed to have a mind of its own. Gmail Checker is light and fast and it unfailingly does exactly as I want it to do. I'm not criticizing Gmail Manager, but for my use, managing multiple accounts, using multiple browsers on multiple computers, I find Checker is like a little sports car. I love it! This is what I needed for so long!
(Tip: I suggest you go into Customize and drag the available 2nd icon up to your toolbars at the top.)