The author's thesis was quite intuitively illustrated by the Google AdSense "Heat Map", which depicted a schematic of your typical web page, with a header, navigation bars down both sides, a footer, and some blocks where the content lay.<p>Heeding the advice of the Heatmap by placing one's Ad Units in the "Hot Spots" on one's old pages quite commonly doubled one's monthly revenue.<p>However the last time I went to look for it at Google's AdSense support site I could not find it. I don't know whether they moved it or took it down.<p>For your own purposes, try placing important links at different places on your pages, leave them there for a week - as the traffic to most sites tends to be cyclical with a one-week period - then analyze your web server logs so as to determine how many internal referrals to other pages on your own site resulted from each link.<p>I analyze my own logs with Analog (<a href="http://analog.cx/" rel="nofollow">http://analog.cx/</a>) which is powerful and configurable but has a steep learning curve. If you don't have the headspace to Read The Fine Manual, there are many fine competitors readily available.<p>Each subsequent week, move each of those experimental links to a distinctly different place on your pages.<p>Upon finding the most-effective placement for each link, put all the links in their best places, then try altering their presentation: text color, typeface size and style, backround color and the like.<p>Once you've found the best combination of everything, you will be in a good position to earn some coin via PPC ads.<p>I myself for three solid years earned $3,500.00 per month on the average, $5,000.00 for two different months, with just two Ad Units on just one single quite lengthy, well-researched piece on copyright law:<p>Links to Tens of Thousands of Legal Music Downloads<p><a href="http://www.warplife.com/tips/law/copyright/music/legal-downloads.html" rel="nofollow">http://www.warplife.com/tips/law/copyright/music/legal-downl...</a><p>Come for the links, stay for the law school lecture.