Listen and Write is a dictation tool to practice your listening comprehension. The content comes from video and audio around the internet: music videos, YouTube videos, TED Talks, news sites, and various other websites.
Here’s a video tutorial that is very helpful and will tell you pretty much all you need to know to get started:
You don’t have to sign up to try the site, but if you want to save your scores and gauge your progress, or take a level test, or access all of the content, you need to create an account (free, with e-mail or Facebook).
Here’s one I tried today, which reminded me of another great dictation website: Lyrics Training.