This is a thread dedicated to AdSense tips only. Please no 'good tips' posts. I just want this thread to be pure quality discussion.

TIP 1: Remove the Borders

Remove the borders on your AdSense ads. Visitors eyes wander around the screen, and borders stop them from wandering.
Removing borders from your advertisements can lead to a significant boost in your CTR.

PS. If I start a WMP blog in the future I will use this as a blog post and if I use your tips I will link back to you.