Anthologize is a free, open-source plugin for WordPress 3.0. It enables WordPress to be used as a platform for publishing electronic texts in PDF, ePUB or TEI format. The plugin enables users to grab their existing blog posts, export content from external feeds or compose new content directly in Anthologize, then apply outlining, create a custom order, and edit content into a single document for export. Anthologize requires a self-hosted or local installation of WordPress.

Sophie is a free, creative commons authoring tool from the Institute for the Future of the Book and the University of Southern California's School of Cinematic Arts that enables collaboration, reading and publication. Its highlights include an authoring environment that allows users to create complex networked multimedia documents, a reader than opens books in a browser without downloading additional software, comment frames for adding discussions within books, digital libraries compatible with the Sophe iPad app, timeline creation and collaborative book creation. As of version 2.1, Sophie includes HTML5 export for data integrating multimedia content and for use on a wide variety of devices.

Sigil is a free, open source, multi-platform e-book editor, designed for editing books in EPUB format.

Full UTF-16 support and full EPUB 2 spec support

Multiple views: code view (complete control over directly editing EPUB syntax), book view (WYSIWYG), and preview view

Table of contents generator, metadata editor, multi-language user interface, spell checking tool, EPUB compliance validator, support for find and replace

Import, organize, and manage EPUB and HTML files, images, style sheets, audio, video, and fonts

Resources

Source code repository

Current packages

Wiki documentation

Online user guide

Sigil's development blog

Help forum at MobileRead

Translations

Google Books provides full, free PDF scans (and web-viewable versions) of public domain books and magazines, free previews of some books and magazines under copyright, and the option to purchase digital editions of available items to save and read on Google Play, their e-reading platform. You can also find a local library based on your zip code that has the item available. Reader reviews of the items are available and you can contribute your own. Search for authors, titles, as well as keywords and Google will return results with matches in the title/text of the item. There are permalinks to available pages. Highly useful for finding items that contain your keywords in its text.

It has the Google Ngram Viewer as part of its service. The Ngram Viewer is a service connected to Google Books that graphs the frequency of word usage across their book collection

Zamzar is an online file conversion service. Zamzar converts between a wide variety of formats (including support for word processing documents, audio, images, video, and ebooks) and emails the result to the user. There is a monthly subscription fee that depends on the volume of data converted. It also has storage services.

Calibre is a free and open source ebook library management application, including options for syncing to devices and converting between a large number of formats. Calibre also has a built-in e-book editor for EPUB and AZW3 formats.