Well, I think Voicethreads is a great way of offering peer feedback to student work. I used it to distribute their responses to my summative assignment on slopes & equations of lines; the final requirement in that assignment was to provide their conclusions in a creative way. Some did a very simple document, others wrote newscasts and radio interviews, there were the usual powerpoints and three students did animations.
A Voicethread lets me post them all together in a stream. Viewers can then comment on the student's work by clicking on the comment button and providing feedback (text, audio, or video). The example above shows six comments on one slide of a student's work.
Voicethreads really pulled it all together. While I do have to spend some time with the students on how to provide valuable feedback ("Good job" isn't particularly helpful) they did find few problems with the interface and were quick to notice which students had met the demands of the exercise (and the rubric) and which hadn't.
I think this is a great resource for other courses... obviously visual & dramatic arts (since it accomodates video) but also languages and the socials. I'm also thinking that importing speeches on UN topics and then having Voicethreads to critique the arguments might be useful.