The Writing Site- Gives explanation of Expository and Narrative writing. ALso gives examples of prompts. http://www.thewritingsite.com
(Sample link) National Geographic for Kids http://www.nationalgeographic.com/kids/
(Sample Link) White House for Kids http://www.whitehouse.gov/kids/whlife/index.html
http://www.bookadventure.com
http://www.scholastic.com