I came across the ESLvideo.com site and thought it was pretty innovative and fun for students.
It allows a teacher to choose a YouTube video (these are sorted roughly by proficiency bands) with a quiz attached to it. This can be embedded on a site or a blog or sent as a URL link to the students. While/after watching the video, the students complete a multiple choice comprehension quiz which generates a score - and this can then be emailed on to the teacher.
It's a pretty nifty idea. Look at the embedded example below (featuring a clip from BBC's Top Gear which puts a new Aston Martin to the test against a roller-blader with jet rockets strapped to his back...).
Cool - I like it!
:-)