Calibre is an epub file manager (free) that supports any device and can even strip DRM from files! I've been using it for years and I believe that everyone should at least know about it. Here's the manual for those that want to try it.
"Calibre supports almost every single e-reader and is compatible with more devices with every update. You can transfer your e-books from one device to another in seconds, wirelessly or with a cable. And you don’t need any additional tools to do that. Calibre will send the best file format for your device converting it if needed, automatically.
Calibre can convert dozens of file types. No matter where you got your e-book from, it’ll be ready for your device in no time. When converting, you can also automatically change the book’s style, create a table of contents or improve punctuation and margins. Calibre will also detect the format that’s best suited for your device on its own, so you don’t have to bother.
Calibre can also turn your personal documents to e-books or create them from scratch. It can also take all the mundane things that go with it off your plate. It has automatic style helpers and scripts generating the book’s structure."
Calibre is legit. Fully-featured, constantly updated. If anything, it may be a little too customizable. (The tyranny of options, etc.) But it solves every ebook issue I've ever had, and it does it for free. Incredible app.