i was also looking for something like that.
i guess the closest thing i have found would be a slowed down version of cepstral (hope i'm saying that right) lawrence. The problem is that hal9000 had a very ......comforting tone. i can't find anything exactly like it.
i did see one time, and download, a couple of emotional voices like one that whispers all the time, and one that shouts ect. from cepstral. if there was a "calm" voice, that might be the key.
*with that being said, you could (if you were a dedicated freak) use a tone generated voice like truvoice, and modify the @^@#$% out of it!
-the dude