AIS library for arduino
Library makes it possible to decode the content of the AIVDM messages
See http://www.bosunsmate.org/ais/ for information about AIVDM This page is not correct in the example where MMSI is decoded though.
Also see http://catb.org/gpsd/AIVDM.html for message info.
A couple of online decoders: http://www.maritec.co.za/?page_id=1051 http://www.aggsoft.com/ais-decoder.htm