Wow, I'm surprised at some of the responses.
This kid doesn't care about pictures -- she devours words. She likes books like the Chronicles of Narnia series and The Tale of Despereaux. She will happily read 300 pages in a day if given the time. She'll be overseas at a family member's house for a month this summer and can't pack more than a half-dozen or so "real" books. That will keep her busy for about 3 or 4 days. Then she'll REALLY miss books. I thought of this solution because I want
everybody to be able to enjoy the trip.

I know the library downloads expire, but I thought I'd load the thing with a good mix of library versions and regular purchases/free books. This would be a combined birthday present from me and her grandparents.
She is very careful, by the way.
Anyway, thanks for the ideas for things to look into. Had no idea that PDAs were an option, and never heard of a couple of those devices as I just started to look into this. Thanks for the suggestions.