This weekend I have been browsing iTunes App store (I am getting an iPod Touch for my birthday :D). I went to the Laminar Research Apps page and apart from the iPhone 'mini-X-Plane' apps, there was an interesting app called X-Plane Remote. This allows you to use your iPhone or Touch as a mini instrument panel, remote joystick and most interestingly (to me) as a dedicated moving map display. I will probably have to give this a try.
Link Chris, with regard to keeping your head still when trying to tune the radios, I found that mapping the F9 key to a HOTAS button works wonders (although I think I prefer the command line for quick and easy tuning).