Tours to Go

I am becoming increasingly interested in audio tours that can be downloaded and brought with on an iPod, cell phone, or GPS unit. I remember one my dad had of the section of I80 from Auburn to Truckee in California. It was fantastic and we listed to it repeatedly. Here are some of the more recent ones I've found.



Discovery Audio: they seem to offer a wide array of downloadable tours. I'm not sure about production values.



Audyssey Guides: I bought their CD on Boston to research my Walking Boston book and loved the high quality and interesting narration.



Walk Talk Guides: these are mostly in Europe and provide an interesting business model.



Visual Travel Tours: Multimedia tours for the iPod.



Have you used any of these? Do you know of any others that are great? What about cell phone tours or tours specific to museums or other places of interest? What do you look for in an audio tour?



Please jump into the conversation below. I know there are a number of readers interested in your thoughts on this one, and I'll be monitoring this closely all week.