A VoiceThread starts with a multimedia slide show that can incorporate images, text, video and sound. The show is shared online with friends, students, or colleagues who navigate the media and make comments by voice, text, video, or “doodles.” A VoiceThread can also be exported or embedded on a website.
The University of North Carolina at Chapel Hill has used the system extensively. At their information page, look under “What can you do with VoiceThread?” for some helpful demos. And you can learn more by reading “Seven things you should know about VoiceThread,” produced by the Educause Learning Initiative (ELI).
The basic VoiceThread service is free, but there are fees for exporting and some other features. See their Higher Ed Pricing page for a summary.
The rough YouTube video below gives some sense of what the tool is about.