National Geographic and Energizer batteries - another full in rights grab. Avoid like the plague. Excerpt from the rules below:

"No photos will be acknowledged or returned. By entering a photo in this Contest, Entrant grants a nonexclusive, transferable, royalty-free, worldwide license Sponsor and Energizer to edit, adapt and publish such photo in connection with the Contest and promotion of the Contest, and Sponsor may use the photo in connection with the Contest and promotion of the Contest for advertising, marketing and promotional purposes in commerce and in any and all media now known or hereafter known throughout the world in perpetuity, without attribution, compensation, permission or further notification to the entrant, his/her successors or assigns, or any other entity, unless prohibited by law."