There are two kinds of webmasters:
1) those that put Goggle AdSense on their sites and collect checks
2) those that put Google AdSense on their sites,and tweak it, and tweak it, and then collect BIGGER checks.
If you want to be in the second group, I recommend Joel Comm’s Google AdSense ebook.
Joel’s a friend of mine, and I’ve known about his success with Adsense for many months now. He’s been my “private” AdSense guru for some time, but now he’s gone public with his knowledge. If you publish anything online, I recommend getting your hands on this book.