Interactive Encyclopedia Timeline (left)

This is the left-hand side where it shows you the current year range, as well as lists out all of the dates and what happened on that date (why it's significant). This is a great tool for research.

You'll also notice the Google map at the top, and the "Map Related Articles" link under each date. When you click that link, it will look at all of the articles for that date, collect their geo-attributes, and plot them on the map with info-window bubbles. This is great for things like the Civil War, where battle locations are of interest.

The "Related Articles" link makes an ajax request and pops up a facebox with all of the related articles, and a split-out of why each article is significant to that date.