Adsense is a Pay per click programme. You only get paid if someone clicks on the ads. The payment per click also varies depending on which ad is clicked on.
Google pays per clicks and also per impression basis...it depends upon the advertisers selection and relating ads been shown on your site.
You get a tiny amount of money for _some_ impressions, (hardly ever happens, but it does), and a varied amount for each time a visitor clicks on an advert, (anything from $0.05 to a handful of dollars). You can get paid by checks or by direct transfer once a month if you have at least $100.00 in your account. FFMG
Adsense does anything but "suck" there are hundreds of users on this site including me that make well over $100 per month on Adsense. Maybe Adsense is just not the right revenue stream for your website. Or perhaps you just need more traffic to make Adsense more worth while.
Sorry guys, I never knew that Google paid for impressions as well. I guess you learn something each day!