Increase your Adsense Revenue:

Add "Google.com" to your Allowed Sites list if you restrict your Adsense ads to certain sites on your Adsense account. 

Adsense URL Whitelist "Allowed Sites" Background:

Basically, Google's Adsense lets you add a list of URLs that are allowed to earn credit for your account. Your Publisher ID is displayed in every ad, and someone that wanted to could use this, put it on a bunch of questionable sites and get you banned from Adsense. So, if you think you have any enemies or competitors that want to slander you, definitely set up one of these whitelists. 

So, Google lets you set up "Allowed Sites"

Now, Google shows which "Unauthorized Sites" used your publisher ID in the past week.

My Adsense "Unauthorized Sites" list:

Interestingly, the first three URLs, when you do: "http://xxx.xxx.xxx.xxx", I get sent to Google's Search Engine. Doing a traceroute shows that these URLs indeed do belong to Google.

Here's what I think is happening:

Whenever someone does a Google search and my sites show up in the results and then visit my CACHED page, that page has Google's URL, not mine. I suspect that I wasn't earning credit when such pages were shown.

So, to increase your revenue a little bit (and perhaps a very small bit), add "Google.com" to your "Allowed Sites". I'm assuming that "Google.com" is sufficient, rather than the IPs, but I'll determine that in a week's time.