I do not know how long Google has offered this, but I just noticed today that you can add themes to your personalized home. There seems to be only about half-dozen to choose from at the moment, but I am sure that will change. I personally have chosen the “Tea House” theme. I tried a most of them, and the all the ones I have tried track what time it is, given your zipcode, and update the header image accordingly. I took this screenshot in the evening, but earlier today, it was bright and sunny and the fox was rowing in his boat! I know it’s not the most amazing thing on the web, but I find it pretty cool. Also, the image does just fine on the widescreen resolution.