This site, produced by the University of Oregon, features lots of animated maps illustrating problems, patterns, and events throughout history. Mapping History is essentially a digital atlas of American, European, Latin American, and African history. Each section is divided into modules based on historical themes and eras.
" 'Impossible!' you say? Look, we can't grade the essays for you, but we can reduce the repetitive, inefficient manual labor involved - and in doing so we open up a new world of invaluable student data."
This is in Beta version so it is being offered for free at the moment. It sounds like it will eventually become a paid service - but maybe it's worth the price for those of you that grade a lot of rubric-based essays.
"Announcify is a free text to speech application that is available as a Chrome browser extension and as an Android app. With Announcify installed in your browser any time you're viewing a webpage you can simply click on the Announcify icon in your browser and have that page read to you. "
Zotero [zoh-TAIR-oh] is a free, easy-to-use tool to help you collect, organize, cite, and share your research sources. It lives right where you do your work-in the web browser itself.