Couple of links that might grab some attention from others.

First, Wikipedia:
http://en.wikipedia.org/wiki/Voiceroid

Some demos:

I'm not particularly in a market for teenage girls characters but I am impressed with the quality of the voice.

That's pretty dang impressive I have to say. Much better than Vocaloids, which just sound like really bad freestyle rapping when made to converse. I can't really think of any actual uses for this though, but I'm sure someone more clever than me will think of something amazing.

Wow. Anki. Plugin.