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.

Commentpress is an open source theme and plugin for Wordpress 3.3.1 or later designed to enable readers to contribute comments to each paragraph of a text and display those comments in the margins. Commentpress turns a text into a conversation, whether a blog or a fixed document such as an essay, book or article. It may also be used to add a gloss or annotations to a document. This tool is also available for BuddyPress and BP Group Blog.

The Text-Image Linking Environment (TILE) is a web-based tool that enables users to select regions of an image and link them to text. TILE is a system for creating and editing image-based electronic editions and connecting them to digital archives of the texts. It has been designed for easy modification by integrating a plugin infrastructure.

Scripto is a lightweight, open source tool for crowdsourcing transcriptions for Humanities projects. Projects utilizing Scripto can manage contributions via full editorial controls and a versioning history.

Edit Flow is a free, open source WordPress plugin designed for editorial collaboration. It includes a private discussion environment, metadata management and workflow tools.

Pressbooks is a platform for collaboratively creating ebooks built over WordPress available as both a free service and on a subscription basis. Subscriptions are only required for users wanting to manage more than 5 books. eBooks can be generated in a variety of formats from several provided templates. Pressbooks integrates functionality for importing material from WordPress, Blogger and Tumblr, and assists in collaborative authoring with workflow management tools.

Digress.it was a free, open source WordPress plugin for annotating texts on the paragraph level, particularly of article to book-length documents. It permitted blog-like threaded discussions to occur in the margins of the text, and was aimed at facilitating scholarly, literary, political and other discussions. While the main website is no longer available, Digress.it is still available via the WordPress plugin directory.

Create polls, surveys and quizzes and get ratings/feedback on content from users. "All languages supported." The free version has fewer options.

At the paid levels there are design options such as customized branding and CSS control; collection options include 10k-50k (depending on purchased plan) of monthly participants and password restriction; and it is in the reporting methods that this program has the most depth: real-time results, charts, the ability to export responses and reports as Excel, PDF, Google Docs, CSV or XML, filtering options, text analysis, tagging, email notifications of new responses, and priority customer service. Also, you can add images, videos, and content from YouTube, Flickr, and Google Maps.

This works with Wordpress.

This was previously Surveydaddy and has been upgraded to Polldaddy.

Participad is a WordPress plugin that allows multiple people to edit the same WP content at the same time. Powered by Etherpad Lite, Participad gives you: notepads for collaborative notetaking; synchronous authoring of any content in the WordPress Dashboard; front-end editing. You can download it from the WordPress plugin repository.

Participad has three modules:

Dashboard – The Dashboard module puts Etherpad editors into the WordPress Dashboard. Participad removes the “Visual” and “HTML” tabs from the standard WP editor, and replaces them with a “Participad” tab.

Frontend – The Frontend module allows users to edit WordPress content from the front end of your website – no Dashboard required. Participad modifies the Edit links on your posts and pages so that, instead of leading to the Dashboard, the static content of your post is swapped with an editable Etherpad window.

Notepad – The Notepad module enables a new WordPress Post Type called Notepads. Notepads are collaborative note-taking documents, which can optionally be linked to existing static posts or pages. Participad provides several shortcodes and widgets that make it easy to create new Notepads from the front end of your website.

N.B. Participad requires a separate Etherpad Lite Installation.

Plugin for Omeka and WordPress that allows you to automatically tweet new additions to your Omeka archive or WordPress blog.