This is kind of interesting. AdSense now lets you choose to have seasonal themes. These are kind of interesting, as they have background images as well as appropriate colors.

Turning them on is kind of tricky. You go to where you select your ad type and change your setting there. There’s a checkbox to turn on seasonal themes.

I’m giving this a quick try, although I have my doubts about it. I’d really prefer that it be set by ad unit, rather than the account as a whole. I’d really like to be able to track the effect. I am not terribly optimistic on its impact on some of my sites, while it would be entirely appropriate on others.