The Mio has a button to add POIs. But then I couldn't find where they were on the device. The short answer is that they are in the file iGO.db that's in the flash drive (not the SD card) on the Mio.
Then I needed to convert them to a format that I could import into something like Google Maps.
To do this I Googled and Googled and finally found iGO POI Explorer. There's a pretty good discussion of it in the GpsPasSion forums. A Google search works pretty well also.
I connected the Mio to my laptop with a USB cable. Then I could see the iGO.db file in \MIOMAP\MIOMAP. Remember that the Mio C320 runs Mio Map v3.3.
I copied iGO.db to my laptop and opened it with iGO POI Explorer.
This is what the POIs look like in iGO POI Explorer.
Then you need to export them to a kml file that Google Maps can import.
From there, it's just playing with Google Maps. I'll make that another post. Maybe you can figure it out before then.
Here's the result.
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