Google has released what they call the first version of their Adsense app for iOS. It's iPhone only at the moment, though of course it'll run, boxed, on the iPad as well. With Adsense for iPhone you can look up key earnings information, top custom and URL channels, ad units and sites reports, and payment alerts.
If you rely on Ad Sense for any of your revenue, keeping your account handy will certainly come in useful. Check out AdSense and let me know what you think!