I really liked the "I am thankful for..." voicethread, because we saw the student's pictures and then we heard them say what they are thankful for. I am a PST in a kindergarten class, and I think this would be a great activity to get the students involved with technology in a simple, yet fun way.
Another voicethread that I liked was the one where the students broke up into groups and came up with their own way to solve the math problem. I remember when I was a student and I always like writing on the white board or anything that made me feel like the teacher. So giving students something they can explore with and do on their own would be fun for them!