Ask E.T.: Timelines on the Internet. Well, first, I think the internet is generally poorly suited to visual communication.
Sure, it's a wonderful thing, but graphics are not its strong point. I have been known to create drawings over 15' long to express ideas and convey information, when I needed to. At 600dpi, that is over 100,000 pixels on one axis. Gwtsimiletimeline - Google Code. Timeline.