These are some of my favorite authors and their websites!
This international site, meant to appeal to the international legions of Harry Potter fans. The graphics are fantastic, there's lots of games, sound effects, information about upcoming events, and Rowling's biography.
Look for the white dog in all of his stories! He sponsors a writing contest every year on his website; 'The Mysteries of Harris Burdick'. He gives students tips on how to become a better writer, and there's lots of games, puzzles and other activities on his site. Periodically, he sponsors a webcast where he answers students' questions about his work. These webcasts are always archived on his site.
This site is sponsored by the National Council of Teachers of Mathematics, and it contains a wealth of resources for families to help their children with math and math homework. There's a daily brain teaser for kids too.
One of the oldest kid-friendly math websites around, this site has EVERYTHING math related--flashcards, games, worksheets, you name it! It also covers every math topic from addition to calculus, so it has something to offer for everybody. It is 'an amusement park of math' according to the site.