Check this out! If you want to encourage your learners to write and speak English this is a great tool to do it, especially with younger learners and teenagers. Xtranormal.com is a site where you can choose backgrounds, characters, sounds, actions etc and make a movie either by recording your voice or by typing in text that is then read back by an automatic voiceover (in a range of accents). It's like Voki, but you can get a lot more elaborate! When you have made one, you can e-mail it, embed it, download it (interestingly), share it on Twitter, Facebook etc etc....
Here's an example:
ICT Blog movie
by: JGakonga
It's free to play with and to make your first couple of videos (they give you 300 points to start with) but you do have to pay after that - I think it's quite cheap, though, and the three or four free ones that you are allowed on a free log in may well be enough for most learners.
