I've developed a new autopilot remote control which uses your iPhone (or iPad) as a remote control by running an app called iSteer.
You can download iSteer for free from the iTunes Store to have a look at it but it only works with my remote control hardware.
iSteer came about because of feedback from people who didn't like the fact that with my current remote controls you can't tell if the autopilot has actually received a command from the remote when you press a button and so the only way to be really sure of that is to somehow display data from the autopilot itself.
Here's a video showing iSteer in action with a ST1000+
One model remote control uses iSteer only whereas a second model includes 2 button fobs to use in case your iPhone has a flat battery or if the weather is too bad to have an iPhone on deck - the best of both worlds really.
Feel free to ask questions!