incrediBILL - 6:33 am on Aug 27, 2012 (gmt 0)
Analyze your stats - keywords are easy to figure out.
For instance, you could assume that if you had a site about cars keywords coming about Ferrari's might pay better than keywords about Fords.
It's also about intent, a query about "buying fords" or "repairing fords" probably pays better than "what's the most popular ford color" - a little common sense applied to how people are getting to your site and where they are coming from can work wonders.
But we're back to web basics called SEO and ANALYTICS which has is what also drives AdSense.
If you don't know which keywords pay more it's easy to find out, get an AdWords account and try bidding on some of them and you'll find out real quick what's costing the most which will also pay the best.
However, if your site mostly attracts penny traffic you have other issues IMO that need to be addressed because AdSense isn't placing much value on your site in the first place.
Later in the day it may be 50c, tomorrow 10c.
Or back to $0.01