Here a few that I took an interest in from the list:
VideoNot.es - Makes it easier to take notes from a video.
Quizlet - Yes, now an app/extension for Chrome. Create review games and flashcards for terms.
Hangouts - For Teachers, you can chat (text, video, or audio) with other teachers in D140.
Lucidchart - Create flow charts and diagrams. Great fpr brainstorming.
Newsela - Daily news at your students' reading levels (grades 3-12)
Biology Pop - Content specific and very useful site.
3D Solar System Simulator - This drew my attention instantly, and I spent way too much time playing around with this on my own. Very well done!
Awesome Screenshot: Capture & Annotate - Ever needed to direct students where to go on a website? Make it easier with screen shots and written directions.