Here are a few free sites for creating multimedia timelines.
Great for older students, XTimeline can include text, images, and video. XTimeline will accept dates in A.D./B.C. format.
An easy to use timeline that is a suitable choice for students in elementary school or middle school.
TimeRime allows users to create timelines that include text, images, audio, and video.
Dipity is a great timeline creation tool that allows users to incorporate text, images, and videos into each entry on their timeline. Dipity also incorporates a mapping feature which allows users to place a Google Maps bookmark related to the topics the timeline covers.