RegExr - RegExr.com is an online tool to learn, build, and test Regular Expressions.
calibre - Ebook manager, viewer & converter
Expresso - The award-winning Expresso editor is equally suitable as a teaching tool for the beginning user of regular expressions or as a full-featured development environment for the experienced programmer with an extensive knowledge of regular expressions.
Amazon Kindle - Amazon Kindle software lets you read ebooks on your Kindle, iPhone, iPad, PC, Mac, BlackBerry, and...
Cool Reader - Fast and small cross-platform eBook reader for desktops and handheld devices