Watch videos in English with captions. Click any word to get pronunciation and a definition. There is another mode to use the videos as cloze exercises with immediate feedback. Includes social features for competing against other users.
Site offering a variety of apps that teachers can use to create activities and that students can use on their own. Intended for EFL, but would also be useful for other languages in some cases.
Limitations: As of 6/9/2016, no new registrations are allowed, although the site can be used without registering.
Online language lab. Allows you to create speaking, listening, reading, and writing assignments that students do online. You can provide feedback to them through the interface.