Mighty Optical Illusions make great writing prompts. I'm always on the lookout for interesting or strange paintings, photographs, etc. to inspire student writing. I have the MO Illusions widget installed on my iGoogle page, so I get a new one sent to me every day.
For more fun writing prompts, I recommend Googling the terms "Guinness Word Records" or "Ripley's Believe It or Not." You can also check out the Snopes website; they have some interesting pictures under the Fauxtos section. If you want something less strange, but equally inspirational, check out the Photo of the Day on the National Geographic website, and search their database of past photos.
Dr. Jessica Pilgreen, Ed.D.