The extension, known as the AdSense Publisher Toolbar, offers a summary of your AdSense earnings for the current day, the previous day, the current month and the previous month. In addition to daily earnings data, it also show revenue data for top channels that you have created in your AdSense account.
There’s an interesting “lifetime revenue” section in the report that shows your total AdSense earnings from the day your account was approved for AdSense.
Once you install the extension, it connects to your Google AdSense account using OAuth and then uses AdSense APIs to fetch your earnings data. You need to authorize only once and thus, if you enjoy checking your AdSense report every hour, this extension could save you plenty of time.
If you have multiple Google Accounts now you won’t have to switch accounts in order to be able to view basic data on your Adsense account.
On a different note, I have no idea why the Google team is calling this extensions the AdSense Publisher Toolbar when it only adds a button near your Chrome address bar and there are no toolbars anywhere. You click the AdSense button and your earnings report are almost instantly display in an overlay.
And if you activate the AdSense extension while you are on your website (that is running AdSense ads), you can turn on the “site overlay” mode and it will display a quick summary of each ad unit’s earnings that are available on that page. Channel names are confusing, especially when you have tons of them, so this visual mode will come very handy.