Today, when I logged in to check my revenue from Google Adsense, there was a notification on dashboard. It was actually a recommendation to change a smaller ad unit to a larger one. It was suggested with optimist of increased revenue by up to 45 %.
I remember few month ago there was a suggestion to replace 200-250 pixel wide ads with 300 pixel wide ads. After a thought, I made required changes in theme and had accommodated that and it really worked. However, this time as the recommendations says replacing a 468 pixel wide ad with a 728 one would be a bit harder to adjust.
Let’s see if I can incorporate this one too in the current theme with some effort 