The Internet is a wonderful source of unusual information. I can't recommend anything in areas outside astronomy. But if you look at some of the sites in my hotlist, and let your imagination wander a bit, I'm sure that something you might stumble across in one of these sites will inspire you to ask a question suitable for a science fair project. Remember, the best topics come from the simplest questions you can think of. Try to write down one or two questions that come to mind from each of the sites you visit. Have a look at the ones that display image data, and study the images for something that catches your eye. You might start with my COBE infrared images of the sky. Much of what you see has not been investigated in detail by professional astronomers.