[GPSNavX]

I use a Shipmodul BT Mux and it works great. Accepts NMEA data from GPS, Instruments and AIS, outputs NMEA data to Autopilot.

http://www.shipmodul.com/en/miniplex-bt.html

Once the NMEA data is into MacENC it is rebroadcast over an AdHoc WiFi network to iNavX running on iPod Touch or iPhone.