My Take
Voki is a website where you can choose from several customizable cartoon avatars. You input typed words, call in or record audio to make your Voki "speak." The free version is quite limited in the selection of avatars, but it's a fun option for short text-to-speech projects. The text-to-speech is also available in several different accents.
How I Use It
As a Spanish teacher, I have used Voki as an introduction avatar greeting visitors to my class webpage. I chose an avatar who most closely resembled me, and then typed in a welcome message to my visitors. I have seen other teachers use it for language listening activities, however, the text-to-speech is very robotic-sounding, and not very authentic, so I would not recommend using it in that way. I have yet to use the VOKI to record student's voices. To do that would require an educational subscription, of which I'm not willing to pay, as there are other free sites out there (Google Voice) for students to record their voices.