I have been experimenting with different position, colors and ad placements until recently when i took the site down for a few hours and build the theme from the ground up and made ads wrap around text and after doing this my users have been seeing revenue increases. In a day no i make $50 i'm not sure how much my users make but i have seen improvements on my ad impressions and clicks. for an example you can take a look at the following link and see what i mean http://mashbite.com/Health/Tuberculosis_TB_was_a_disease_rampant_in_1940s_Dublin_Ireland Your feedback is needed
Nice ad placement, but you should be careful because you have title "Similar entries" above the second ad block, that is against adsense's tos, I'm sure you are aware.. Also the third ad on the bottom right column is not very useful I believe. You should use custom channels in order to track ctr, cpc, ecpm of individual ad block so you can make good decisions.