Some small test recordings :
http://www.spokentext.net/recordings/mstram/
The voices are not bad for computer synthesized, the best two are ‘Dave’ and ‘Avery’ (female).
Could be useful for creating scratch audio tracks for char animation.
Mike
Hey, Youtube can do this, you can do sound preview your text comments. And the quality is not bad.
But this samples are better of course.
I have been using this:
http://www.research.att.com/~ttsweb/tts/demo.php
Putting the wrong language in is fun (i.e. Spanish text to a German speaker). 
Cool for converting articles to speech:
http://www.spokentext.net/members/micewhat/Why_I_think_911_Was_An_Inside_Job.mp3
http://www.readthewords.com/ isn’t too bad, I was playing around with it some time ago.
I need to find a really good one so I can convert books to audio to listen to when I’m at work. Project Gutenberg has an automated system based on festival I believe but the voices aren’t that good.