NextUp software offers some apps that allow you to read different kinds of documents and text windows (PDF, docs, clipboard, etc.). While checking out their site, I noticed that they are offering for immediate download all of the older Lernout & Hauspie text-to-speech engines! Very cool... [only now I see there's a catch! You can't use them on any other speech apps other than with NextUp's!] There are 10 engines for English and two each for British English, Dutch, Spanish, German, French, and Italian. That’s 24 in all.

http://www.nextup.com/TextAloud/SpeechEngine/voices.html#morefreevoices