Over the past several decades, tremendous progress has been made in the use of computers as chess-teaching tools. Some programs are specifically designed to teach chess to kids, such as Chesster. You can find it at Chess News. (Click the Shop link, then "Search" at the top of the page and enter "Chesster" in the Search bar.)
As a premium service, Chess.com provides a comprehensive library of instructional videos and a child-safe site, ChessKid, offering appropriate lessons, videos, and tactical quizzes.
Many sites, such as ChessCafe.com and ChessUSA, include chess videos and book reviews.
Plenty of online sites offer free instruction: Chessopolis offers extensive links to chess tutorials and lessons. Another information-rich site is About.com.