Even thought this is an old thread, I thought I would respond to it because someone mentioned sending your photo to NATIONAL GEOGRAPHIC.
A word of caution to anyone considering doing this, if you value the copyright of your photo.
Any submissions made to National Geographic should be precluded by a thorough read of the agreement between you and Nat Geo. When you submit a photo to them, you grant them the right to use your photo any way they see fight, in perpetuity, for ever. Their only obligation to you is to credit you in the copyright line.
In effect, you have given them your prized photo, forever. If you are happy with this, by all means, send them your photo.
Most people do NOT read the fine print when it comes to contests or even submissions. READ THE FINE PRINT. Many contests that seem innocuous on the surface, are really nothing more than a blatant copyright grab. By simply entering your image, you give the "contest managers" your image for ever for them to sell as they see fit, with no compensation to you in any way other than a credit.
These contest should be avoided like the plague!
Canadian Outdoor Photography recently published an article on this very topic in the last issue. Well worth a read because the consequences can be bigger than you may think, under certain circumstances.
Any contest, publication or any media that asks you to submit an image or video and then states it has the right to use your work in perpetuity for ever, should be avoided at all costs. National Geographic included. They are the WORST, in my opinion.
If you don't care, then by all means, indulge yourself, but read the article in COP first. Especially, if you are submitting images with people in them!!!