If you don't have a camera, now is a good time to buy one. You will regret returning from your trip with no memorable photos from your experience.
If you have a digital camera you can find all the accessories you need in Greece, including batteries, storage cards, or cables but they might be more expensive. In most Greek cities you can take your card to one of the old 'One-Hour Photo' shops to have your photos printed on paper, and to burn them on a CD or a flash drive within a few hours.
Of course, you could also use an internet caffe to upload all your camera photos to your "cloud" (such as facebook, Flikr, Picasa, and all that) while enjoying a drink.
Also see: Photographing in Greece