I have seen this tactics in some website/blog for showing adsense ads in the middle of post. And i also think that this idea about put adsense ads in the middle of post is a great way to increase adsense CTR. And if you want to increase yuor CTR, you have to try this one
Put Adsense ads in the middle of blog post
Go to your blog account, on your blogger dashboard, click on Layout Menu.
Select Edit HTML tabs, and click on 'Expand Widget Templates'
Don't forget to backup your current template!
After you check the 'Expand Widget Templates' and backup your templates, you have to find this block of code:
Next, replace it with this block of code:
<div expr:id='"aim1" + data:post.id'></div> <div style="clear:both; margin:10px 0">
Note, that you have to change the red code line (<!-- Your AdSense code here -->) with your adsense ads code
Don't forget to save your template before seeing it's result.
But before you can see the result, you have to put this code in every blog post:
|<!-- adsense -->|
in the exact point you want to show your Adsense ads.
More about adsense trick ?