Flying Firsts
PBS has a great site called Flying Firsts. The site is graphical and interactive. As you click through different milestones in flight, you can click on one and it will expand with more details. I use it in a section on flight with my physics class.
Flying Firsts is part of the Scientific American Frontiers section of PBS's site. This section has a lot of great educational resources relating to science.
PBS has a lot of other great educational resources at their PBS Teachers site.