Such a complex and far-reaching subject. For now, I'll just touch on a few options.
Safe Search Engine
http://www.kidrex.org/). This is technically a Google custom search engine but it is touted as "safe search for kids, by kids." When searches are conducted, advertisements appear at the top of the page as well as in the right margin, however, unlike a traditional Google search, the ads are clearly marked in bold "Ads by Google" and appear in boxes. The hits appear in "safesearch on" mode. On the splash page, the search box is large and easy to identify; the type is large and easy to read. These are terrific accessibility points for younger readers.
Social Networking Sites
http://www.onguardonline.gov/topics/social-networking-sites.aspx) at their OnGuard Online site. The FTC site also includes games like "Friend Finder" and "The Case of the Cyber Criminal" to graphically drive their safety lessons home.
The American Library Association (ALA) put together a 23 minute video for Choose Privacy Week that includes visual examples of why it is important to watch what you put on social networking sites (and other Internet sites); the video is available on Vimeo (http://vimeo.com/11399383).
Media Message Overload
http://mediameltdown.net/index.html) provides a starting point or additional resources for media literacy training.
The National Security Agency created CryptoKids: America's Future Codemakers and Codebreakers (http://www.nsa.gov/kids/home.shtml). The site includes games, with badges awarded, that support the National Cryptologic Museum. But they've included cyber-safety games as well.
http://pbskids.org/webonauts/). Cyber safety is the theme of the challenge to graduate from the Academy. Although the site is intended for students aged 8-10 years, it could appeal to younger students with assistance and even older students for whom cyber safety is a new lesson. I think this is a remarkable resource for teaching Internet safety in an engaging way that will reinforce the lessons in a memorable way. Don't miss this one!