Grammarly (Chrome extension and iPad app) makes the writing life easier for teachers and students. It works on Google Docs and websites to help correct spelling and grammar mistakes. 

The name says it all. The Read Aloud Chrome extension reads aloud the text of any website, in the language of your choosing. This is a great tool for struggling readers. 

Power Thesaurus makes it easy to find synonyms and antonyms. Once the Chrome extension or app is installed, just double click a word to get going.