I have a Mac AIS product in development. You can grab the beta from the website, but this forum won't allow me to post the URL. Google for "skunktracker mac ais" and you'll find it; new beta went up a couple of weeks ago). It uses any combination of external AIS data
radios and network connections. The receiver configuration is a bit painful right now; contact me offlist if you need help. Runs on G4/G5/Intel Macs running Tiger or Leopard.
Hal