Another site I explored tonight: http://mnemograph.com/
Blurb is "free, web-based timeline software
for creating and sharing
history and project planning"
Click on the sample Wright Brothers timeline to see all it can do. I especially liked the ability to add comments and links. I think this might be a great way to teach a period of history and have the students see the connection. I could see creating a lesson and using theis to provide the notes for students to study from.
The instruction page looks really good and you can share them via a separate link that will be created.
"Can I share timelines?
Yes. Mnemograph is both an authoring and a viewing tool. Click the 'mode' button to preview the viewing mode. If you choose to make a timeline "public", a URL will be created for it which you can send to anyone and which they can view (without being able to edit or create events themselves). We'll also be able to give you some html which will let you embed a timeline within another web page."
Again don't know about viewing at school but it sounds like a great teaching tool!