National Geographic Kids is currently running an international photography contest for kids!
Kids ages 6-14 living in the United States (excluding Puerto Rico) and Canada (excluding Quebec) can enter in three different categories: Animals, Scenery, and People. You could win a camera and an autographed copy of Annie Griffiths Belt's book, A Camera, Two Kids and a Camel: My Journey in Photographs. The contest runs through November 3, 2008. Check out this link for an entry form, contest rules, and other information.
If you live outside of the U.S. and Canada, check out The Worldwide National Geographic Society International Photography Contest for Kids for a listing of regional contests around the globe. (I wish I could enter in the UK -- you could win a safari to Kenya!)
Regional winners are entered into the international contest and "one Grand Prize winner will win a five-day, four-night trip to Washington, D.C., including a special tour of National Geographic headquarters ..." (I still want to go on safari!)