If there’s a wikipedia (or any kind of encyclopedia, actually) which focuses in events and shows its content in timeline manner (equipped with maps, video, photo, and mashups from different web services), that would be a super awesome tool for learning history.
Imagine lots events overlapping throughout the century.
Imagine having birds’ eye view to human history. Zoom out to see the whole picture, and zoom in to see the detail event.
Imagine having visual maps of human history. Ah, an event here is followed by another event there.
That would be super awesome.