NASA for middle-school students http://www.nasa.gov/audience/forstudents/5-8/features/index.html
National Geographic for Kids http://www.nationalgeographic.com/kids/
Learn Spanish http://www.studyspanish.com
Say it in Japanese http://web-jpn.org/kidsweb/say.html
Primary French http://www.bbc.co.uk/schools/primaryfrench/