I've had Palm's and PocketPC's for about ten years now (got first Palm Pilot Personal in 1996, and my first PocketPC 4/19/2000 the day they were released).
I've discovered that the Ziploc bag is one of the best technological inventions

I've used it to read ebooks on the beach -- no sand in my device! Works great in the jacuzzi too, heh heh. So I'm guessing gallon-sized Ziploc bag for the reader?
They actually make some pretty nifty "dry bags" for gadgets now, but I haven't purchased one yet.