Gmail is Google's golden child, but it isn't perfect. It's full of numerous user interface elements you don't necessarily want or need and there's no way to turn them off. Gmelius offers you a way out of ads, the people bar, and more while also making Gmail easier to navigate. It's a great extension, it's free, and can dramatically improve your experience in less than a minute. More »
If you don't need notifications for every Google services under the sun (as provided by One Number) and you're just looking for a solid GMail notifier for Google Chrome, have a look at the Google Mail Checker Plus extension.
I haven't encountered many Chrome extensions which utilize the desktop notification functionality, but what better place to put it to good use than a mail checker? Install GMC+, wait patiently for new messages to arrive, and you'll get slide-up notifications whenever a new message arrives in your inbox.
GMC+ also includes a long list of customizations via its options menu including audio alerts, ten different icon sets, and more languages than you can shake a stick at. Google apps accounts are also supported.
It's well worth adding to your Google Chrome install if you're a GMail user.