National Geographic hosts their international photography contest every year showcasing images submitted by readers from all over the world. The photographs are then voted on by readers and the top ones are selected.
25 images from among this year’s entries are featured here: http://www.boston.com/bigpicture/2009/11/national_geographics_internati.html
Top Photos from previous years: http://ngm.nationalgeographic.com/photo-contest/past-winners?startgallery=1
Some great wallpapers from these photos: http://ngm.nationalgeographic.com/photo-contest/2009-wallpaper
Selected photo galleries: http://ngm.nationalgeographic.com/photo-contest/2009-galleries