Just a brilliant concept, and great implementation. WhoWhatWhen does "Interactive Historical Timelines" from 1000AD to the present. For example, you can look up a person and see their lifetime on the graphic timeline. Overlaying that you can choose to display wars, inventions, lifetimes of famous politicians, and so on. Hovering over a bar on the timeline brings up more information, and clicking jumps into the search engine of your choice [via Bud].