wow, what a thread.
OK, there needs to be some input from the other side. My earnings have been going up for four years straight. I was in from the start in 2003, made a packet and then saw a slow bleeding off and 2009 and 2010 were just awful, was ready to throw in the towel.
here's what I did:
1. I stopped caring about G. Even though adsense revenue is about triple what is was four years ago, it's now only 10% of my total income, instead of an eggs-in-one-basket 80% that it used to be. How you do that depends on you and your site. I decided not to be a hostage to them any more.
2. I stopped caring about adsense. I check my stats once a day, well it usually ends up 4-5 times a week. I've used handy tools like the experiments but I do not, I NEVER, obsess over stats. If you're logging into adsense 27 times a day and sweating over "CTR down 10% from its usual noon figures", I'm sorry but you are part of the problem, not a part of the solution.
3. If you're not obsessing over adsense stats, you can work on your site. I've taken my site from 2k pages to 6k pages in the last four years and these are not "product pages" fluff, those extra 4k pages are equal in quality to the initial 2k.
5. Build your site for visitors, not Google. Google themselves tell you this. Do you follow this advice or not? If you tell me, as someone in this very thread has done, that you "have done nothing but improve my site" and then tell me the next sentence "I spend four hours a day on this forum", then there's a sharp contradiction in there that you need to address. Working on your site means just that. Get out of adsense, stop checking your stats every seven minutes, stop trawling these forums for magic bullet solutions. Improve your site, think of your visitors, add quality content.
Diversify. Rectify. Technically Beautify.
My oh my.