I was looking for an easy to implement plugin for management of Google Adsense. The AdSense Integration WP QUADS plugin is free and has some pay options, but for me at the moment, the free part works just fine.
It gives you the ability to assign multiple ad units that can be used to rotate through the main posts, and also allows you to set up ad units for use on the side bars. It was very easy to install and configure. I would highly recommend it to new users of WordPress when setting up their blog with Adsense.