What makes a photo interesting?

depth of field is so overlooked, when people see something they want to take a picture of, they focus solely on the subject. I think allowing other objects to support the main subject is one of the easiest ways to enhance the quality of the photo.

the meaning of the picture

like any piece of art it is the feeling it evokes. I feel that a good picture pulls on past emotions or makes us remember somthing pleasing in our past. So content that relates to all is important

Asymmetry and depth. Remember "rule of thirds." Divide your frame into top third, middle, bottom, and/or left, middle, right. Depth can also be divided into thirds-- foreground, middle ground, background. Stand far away and max zoom on your subject to sharpen your subject against a softer focus background. Look for or create relationships between the elements of the photo. Have people touch or look at each other, but in a chain instead of in pairs. The photographer/viewer can be part of this chain. Also, shoot people with the camera at chest level, or choose a high or low angle for effect.

I think the expression on a person's face makes a photo. If you can get a "non-staged" and natural look on someone's face..I think that is perfect. Sometimes the perfectly "caught" photo will almost let you see into the subject's soul.

This question is kind of along the same lines as "What makes a song good?" ...hmm I'll guess I'll ask that ...

I agree with glial. Not an easy question to answer. One of those "I know it when I see it," things. When I was editing photos, I almost immediately tossed out those shot at eye level. There is a difference between a snapshot and a photograph, and many times, the camera's point of view is that difference.

So many good answers so far. What's interesting to one may not be to the other of course. Award winning photos a lot of times, are the ones that really tell a story and display an emotion or message without the need for words. Photos that sell are sometimes those that are neat, clear, somewhat typical and straight to the point Like an illustration/diagram. A bad photo of a great/famous person may be more interesting than the most candid shot of a child showing emotion etc...
Before you delete it..maybe post it on flickr or elsewhere and get an idea from comments or ratings.

Keep trying different things with your photography. Sometimes a simple snapshot is a good way to capture what you are experiencing. Othertimes, you want to use other techniques to capture the subject. All the one's you mentioned in your question are good and the other answers add other techniques to try. Lighting and angle are two other techniques to try. Keep shooting and trying new things. A beginning photography class is also a good way to improve your "photographic eye".

The right light, the right timing and evoking an emotion or telling a story without words.

I like pictures that write a story, or sing a song, or paint a picture. You know. Crossing over different arts.
Then again I never was a great photographer.

More and more I think photography is all about the moment. Whether of people doing something interesting or telling, or the way the light falls on a landscape for a brief instant. Sometimes photos are most interesting when the right moment happens to combine with great composition and aesthetic details like colour, texture etc.

It’s interesting to think about what makes photography art [link removed by Fluther]

The memory of the photo is what makes it interesting. The reason you took it, every time you look at it you will relive the momory. Its the story behind the photo that makes it interesting, the purpose of why you took it.