Amazon just came out with a new version of their eBook reader, the Kindle. It looks very nice. I wish they were available here in Japan (my guess, they will be here by the end of the year.
But another service, Google Mobile, allows you to get electronic versions of books on your cell phone. As screens on phones get easier to read, this may be something you could use to help your students maintain their reading, in places like bus stations and trains. Google just added 1.5 million new books.
Read here about why the paper book is pretty much doomed to a very small niche market in the very near future.