If anyone would like to share AIS data,please check with http://www.fleetmon.com/products/ais_partner
Lot of amateur radio operators do share with some web site and everyone is welcomed.
You can find more about shipplotter software at http://www.coaa.co.uk/shipplotter.htm
or if you prefer to use your sound card please visit http://groups.yahoo.com/group/aismon/
You can use your VHF radio/scanner and tune on 161.975 and 162.025 Mhz and try it if you live near shore or busy river.
Shipplotter group can be found at http://groups.yahoo.com/group/shipplotter/?v=1&t=search&ch=web&pub=groups&sec=group&slk=1
Some hams even use it for VHF tropo indicator.