Worldwide Ship Tracking

This is so cool.  An article at Watts Up With That? about the dearth of ships using the supposedly now ice-free Northwest Passage points to a web page that uses meteorological data transmitted by ships (I suspect entirely non-military ships) to plot where they are.  There are breakdowns by cruise ships, tall ships, research ships, and a few other interesting categories, and you can zoom in by region.  It is amazing how many ships are out there.