It will be interesting to see how expanded cooperation with Google will affect access to NASA's wide-ranging collection of on-line educational and technical information. With so much information spread across so many sites, it can be hard to get a handle on what's out there, though if you are looking for something specific enough, the simple Google trick of adding site:nasa.gov to your search string will at least keep you in NASA's domain and avoid the need to search multiple NASA sites with their own search tools. Maybe Google will make the overall organization and access more obvious.
In the meantime, the abundance of riches means that you can look for one thing and often find something else that's even cooler. Case in point: PlanetQuest, a JPL-hosted site devoted to various current efforts and future NASA missions for finding planets around other stars. This site has some wonderful multimedia content, including a narrated Flash overview, and a recently added interactive tour of Saturn's moon Titan (access from the main page). There is also a gallery of all the multimedia content (games, simulations, movies). One nice one is the "3D New Worlds Atlas" shown here, which includes a narrated guided tour.