http://www.voki.com/ - kinda off topic but this could be fun (tho' for me, it's a little rattling, much like MTV, because the mouth movements don't really coordinate with the speech. I don't even mind when it's a time delay - much ;) - which there is on our cable, but when it's just *wrong* because the graphics can't handle it, it's like sour notes. And now I'm trying to dredge up the memories of the Baldi research about how people processed speech when the lips didn't match, or soemthing like that).
This is one of those things that some teachers will think "oh! Let's get the kids doing this a s a project!" ... and for some of those kiddos, it will come at the expense of learning the content. It's fun, but be keerful, okay? :)
Here's an example of somebody using it: http://robertfant.com/PMWiki/pmwiki.php?n=ChristiF/HomePage
Not sure why it's a "math wiki" but I'll be exploring it a little.