Great site! Bookmarked for future reference in programming.

You might give it a try editing your theme.html of your chosen theme :)

Assuming I'm using default theme, If I would like to put my Adsense code into the content or below the title of my post, I will be editing theme_blockcenter_c.html and place it after this code

<{if $block.title}>
<legend class="blockTitle"><{$block.title}></legend>
<{/if}>
.

This is just a suggestion and I think it's not recommended here because there might be a module/block available for easy customization.