FontForge - Free (libre) font editor for Windows, Mac OS X and GNU+Linux
calibre - Ebook manager, viewer & converter
Glyphs - Make everything from dingbat webfonts to full-fledged text typefaces in the most Mac-like font...
FBReader - FBReader is an e-book reader for various platforms. Features:
FontLab VI - font creation and editing, including variable fonts and color fonts
Google Play Books - Google Play Books lets you search, preview, and buy millions of books using Google Book Search.