AIS Receiver USB dongle

According to the latest news, the company producing this item is no longer on the market.
This AIS receiver is cheap , consume almost no power and is simple to connect (USB dongle):
http://www.radargadgets.co.uk/buyais.htm
It works on Windows with a supplied driver and is recognized directly by all recent Linux kernels (Ubuntu 10.10) as /dev/ttyACM0. Output is NMEA readable by OpenCPN.

Other affordable solutions:
The AIS transmissions can be received by various cheap "TV" dongles. For more information read http://www.rtl-sdr.com/rtl-sdr-tutorial-cheap-ais-ship-tracking/
The RTLSDR plugin makes tuning the dongles simple directly from OpenCPN

Another approch is to use a suitable radio receiver, like Yaesu FT857 + sound card + AISMON under Windows or GnuAIS under Linux.