In 2000 I picked up a Rocket EBook which was the first of the ebooks available. I read quite a few books on it, and had a few magazine subscriptions. Ultimately it got stored after a couple of years use...
I pulled it out recently and tried to recharge the battery...no go. Couldn't find a new one (or NOS) either. My books, which were stored by the owners of the Rocket, were lost when the company folded. The good news, it will hold a charge for an hour or so and you can upload any PDF file.
I'm currently using it to read Jim Butterfield's Machine Language for 64 book.
I don't think I'll ever buy a single-function ebook again. However, the iPad looks like the best alternative these days.