I stumbled upon this about a week or so ago and it has been working great! This FireFox extension allows you to link it to your AdSense account so that you can view your clicks and earnings throughout the day and it is updated every so often so you do not have to continually check the AdSense page. But if you want, all you have to do is right click on the bar and it loads up for you!
You can find the FireFox plugin here: http://code.mincus.com/3/adsense-notifier/
The only thing is nothing is labeled…You can view your impressions, clicks, CTR, CPM, earnings and more but nothing is labeled, so unless you know the order they are displayed in you can get easily confused.
Anyway, its a great little tool for webmasters displaying AdSense on their websites! Check it out.