MarathonGuide has an interactive map of the United States that shows the locations of upcoming marathons. The map is zoomable, pannable and by clicking on a location you can bring information about a particular event. You can narrow your search for marathons by date. The size of the event is reflected in the size of the point that symbolizes it. Surprisingly, this is not a Google mashup - a refreshing change - but it still suffers from the use of a geographic “projection.”

By way of tahiggins.