If you're on the level of digg or myspace, you can earn thousands a day. But for the average blogger getting < 1000 hits a day, you get pennies. Most of my clicks pay me .01 to .05 cents, and it's an SEO site. I know for a fact SEO keywords are expensive. That same site two years ago (before all the changes) made me 5 dollars a day or more in clicks with less traffic. I'm not going to post screenshots here (against adsense terms), but based on the rate over the last year, in order to get thousands (2000) per day, I would need to get 2 million unique visitors per day to my website. Simply put, I steer my clients away from building adsense-only sites, because the changes they've made to it make it a waste of time for most small sites, and only serve to make it uglier.