calibre - Ebook manager, viewer & converter
Overleaf - The online platform for scientific writing. Overleaf is free: start writing now with one click. No sign-up required. Great on your iPad.
FBReader - FBReader is an e-book reader for various platforms. Features:
TeXworks - The TeXworks project is an effort to build a simple TeX front-end program (working environment)...
Google Play Books - Google Play Books lets you search, preview, and buy millions of books using Google Book Search.
Texmaker - Texmaker, free cross-platform latex editor