MarineTraffic.com is a very interesting site for anyone interested tracking ships real-time. This site is an open community project hosted by a research team at University of the Aegean, Greece.
The system is a mash-up, data origiating from AIS (Automatic Identification System) by the International Maritime Organization and Google Maps. The system provides different points of views, including:
- Generic map view http://www.marinetraffic.com/ais/
- Ports with very nice statistics, e.g. http://www.marinetraffic.com/ais/portdetails.aspx?port_id=117
- Vessels, many including photos, e.g. http://www.marinetraffic.com/ais/shipdetails.aspx?MMSI=304448000