I recently got a new Capital One credit card where I can personalize the image on the credit card. So, I went with a cool microscope image of a cracked sol-gel taken by another person in my lab:
μm. Not sure what I'm going to go with for my next one. I have some really nice SEM images, but I'm not sure that DARPA really wants me putting 'em on my credit card. But, I could always submit a "public release" form for those images, I suppose.