So we all know that, in general, pictures next to ads increase ctr. I'm getting conflicting reports about whether the pictures should be relevant or non-relevant. I saw an email from a Google employee that states they should be non-relevant (so as to not lead people to click the ad based on the picture).
They should be relevant, but in a more "general" fashion. Put something up, and have Google review it to make sure it is fine.
It seems that it would be hard to make the pictures too relevant to the ads since we never know what ads we'll be getting, much less in what order the ads will appear. Still, try not to be too specific with your pictures.