The Amazon Kindle is an ebook reader which can be helpful in learning Japanese.
EPWING2Kindle - Converts EPWING dictionary files to Kindle format.
JMDict for Kindle - JMDict in Kindle dictionary format. Good for slang, etc.
Importing Vocabulary Lookups to Anki
FluentCards - A website that can export your Kindle vocabulary lookups to Anki.
Kindle Mate -Software that can export your Kindle vocabulary lookups to Anki.
AozoraEpub3 - Converts Aozora Bunko-formatted text files to Epub.
Converting Aozora Documents to Kindle - A guide for how to convert Aozora Bunko-formatted books to Kindle format.
- How to Use a Kindle to Learn Japanese video - Goes over tips, has link to pre-converted EPWING Kindle dictionaries in the description.