Timelines are standard in the history teacher's playback. Timelines have uses in other content areas too, but I don't know history a teacher that doesn't use timelines at some point in their curriculum. The following are three good timeline building tools. Timelines built with any of these three services, X Timeline, Mnemograph, or Time Toast, can be shared and embedded into wikis and blogs.
I've written about X Timeline and mentioned it on my podcast in the past because I find it be a great service that is very accessible to high school students. Using X Timeline students can collaborate, just as they would when making a wiki, to build a multimedia timeline. Timelines built using X Timeline can include text, images, and video. X Timeline will accept dates in A.D./B.C. format.
Mnemograph is a new timeline service that is still in beta. Mnemograph offers some very nice layout features over X Timline, but is not quite as intuitive to use as X Timeline. The layout features that I like about Mnemograph is the ability to stagger or indent events below each other in a sequence. Mnemograph also makes it easy to display the relative importance of an event by increasing its size in comparison to other events on the timeline. Like X Timeline, Mnemograph accepts dates in A.D./B.C. format.
Time Toast is the simplest of these three timeline builders. Of these three timeline builders, Time Toast is the easiest to learn. To add events to a timeline simply click on the inconspicuous "add an event" button and a simple event box pops up in which you can enter enter text, place a link, or add a picture. Time Toast does not have the more advanced editing options that X Timeline and Mnemograph offer. What it offers instead is ease of use which makes it a suitable choice for students in elementary school or middle school.