At the end of August, Voicethread announced it had added media from the New York Public Library . In addition to the option to upload this new media from Voicethread, there is also a separate site for the library content at http://nypl.voicethread.com/. I have included the voicethread that gives an overview of this feature below.
You also may choose to create copies of your voicethreads; useful if you'd like to create a copy for each class to comment on or for backing up a current voicethread before editing. Although there are different options for accounts in Voicethread, all of these additions are part of the free version. If you haven't looked at Voicethread, its well worth checking out.