Have a look at the following graph :-
There has been a more or less steady rise in RPM from photos-for-you.com since it started, but (provided it holds up) the most significant rise seems to have been caused by my allowing all 'sensitive' categories at the end of November (and opting in to gambling ads - though it refuses to show this as an event in AdSense, and insists changes were made on the 1st November because I am viewing the report by 'month').
The 'sensitive' categories was something I had disabled *ages* ago (so long ago I can't remember) as those categories were giving me a much lower RPM than the average RPM on irishviews.com.
Exactly how much effect this has had compared to enabling gambling ads, I am not sure (but I'm guessing the gambling is the bigger factor having seen how much Google charges for gambling related keywords in AdWords). Either way the lesson to take home from this is that unless your are 100% sure you are doing the right thing, leave all the default settings alone in AdSense, and follow most recommendations Google make. After all, Google want you to make more money so they make more money...
PS - I do feel a little guilty about the gambling thing, but if it it doubles revenue then I guess I can live with that on my conscience (and as far as I know my lovely American friends that frequent the site will not be subjected to these vile ads).
PPS - I know, I'm a hypocrite.
PPPS - The increase in RPM (if it lasts) for December may have nothing whatsoever to do with any changes I have made, but rather down to the pre-Christmas crazy bidding season on AdWords. Though looking at 2011 this wasn't the case.
Make Money From Photos by Jordan McClements is licensed under a Creative Commons Attribution-Non-Commercial-No Derivative Works 3.0 Unported License.