I've mocked up a rough prototype for a sort of slip cover case I'm building (in curly ash, of course) for my son's "Kobo" e-reader. It's the Chapters variation of a Kindle.
The original idea calls for a leather strap to keep it secure (where the green tape is in the picture).
Here's the question: if I use a rare earth magnet to keep the strap in place, do I risk messing up the memory of the device? My Blackberry case has a similar strap with magnetic closure, which suggests it's okay.