I've posted this on my blog, but thought people in the greater Classroom 2.0 community might find it useful, too.
The latest site I've learned about is called Asterpix. It allows you to take any video posted on the Internet and easily create "hotspots" in it that allow viewers to click on it and get more information. Here's an example.
English Language Learners can use it to "annotate" videos they make or watch. Both teachers and students can use it to create an added dimension to video quizzes they make using ESL Video.