mobile web documents: ePub

There is often a need for packaging web content as a portable file, like PDF but based on web technologies. ePub is a solution for this. ePub format is a simple zip of a XML index file and HTML pages, and it has an advantage of being flexible for various screen sizes: very important for mobile, and reading text documents.

EPUB - Wikipedia, the free encyclopedia

EPUB | International Digital Publishing Forum

Besides desktop and mobile apps, there are also JavaScript apps for that, even a "app" extension for Chrome web browser. And since future Microsoft web browser Spartan will also be compatible, this is almost universal and simple solution!

Readium - Chrome Web Store

Readium | Digital Publishing meets Open Web

.epub eBooks Tutorial - Introduction: What is ePub? Why should I use it?

There are various tools for creating ePub, some  of them free and open source.
EPUB - Wikipedia, the free encyclopedia (editing)

free tool: calibre - E-book management
How to Convert a Word Document to Epub: 15 Steps (with Pictures)

free tool: Sigil (application) - Wikipedia, the free encyclopedia

Sigil Tutorial - Sigil Overview 

Another popular format for mobile documents is "mobi", a proprietary format used by Amazon Kindle.
Comparison of e-book formats - Wikipedia, the free encyclopedia

free ebook: What is EPUB 3? - O'Reilly Media