Text to Speech

Read&Write for Google 

Read&Write for Google (Chrome Extension)
Provides a drop down menu bar in Google Docs with features including text to speech, translation, and highlighting. A paid version is also available that adds a picture dictionary, word prediction, vocabulary list builder, and more.
Note: There is a paid version with all the tools and a free version with a subset of the tools. Educators can get the paid version for a year at no cost by filling out the form at: http://rw.texthelp.com/drive/home/RegisterTeacher

Immersive Reader (unofficial)

Use Immersive Reader on Websites [unofficial] (Chrome Extension)
Includes a variety of tools to support reading such as text to speech, picture dictionary, translation, font size and spacing, and contrast.  View short How-To video for more information.

Microsoft Word in Office 365 (Online version) Immersive Reader

In Online version of Microsoft Word, Click "view" > "Immersive Reader." Includes a variety of tools to support reading such as text to speech, picture dictionary, translation, font size and spacing, and contrast.

Speak It 

Speak It (Chrome Extension)
Text to speech tool that reads any selected text on web pages or PDF’s that are opened in Chrome. Options that can be adjusted include speaking rate and choice of voice.

Read Aloud

Read Aloud (Chrome Extension)
Text to speech tool that supports 40+ languages.

Click2Speech

Click2Speech (Chrome Extension)
Hover over text and it automatically highlights in the entire paragraph in green. Click anywhere on the paragraph to start the read-aloud. Right-click the extension, then click Options to see settings. Does not track words as it reads.