Just in case you happen to be using the Yahoo! Publisher Network to monetize your site, be aware that they announced that its going to be shutdown on April 30th of this year.
I personally have tried using YPN a few times before and it was waaay behind AdSense for actually making me some money so I’m not sure it’ll be missed much. Interestingly in the email that they sent me to announce the closing, Yahoo even suggested that people using YPN switch to Chitika, which I thought was very interesting. I will admit Chitika is quite good, but the fact that Yahoo stepped out to suggest something shows just how much they hate Google over there.
Frankly, I have tried to join YPN but my application wasn’t accepted. I think Adsense is easier than YPN on how to be a member.