Babble makes your computer speak to your best friend or your worst enemy. You can even save the spoken content to file or send it as an email.
Use it to improve your pronunciation of foreign languages
or to have some fun on the telephone.
OS X Lion includes voices that speak 22 languages: Arabic, English, Czech, Danish, Dutch, Finnish, French, German, Hungarian, Italian, Japanese, Korean, Norwegian, Polish, Portuguese ... Just download them in the System Preferences (type tts in the system prefs search field and goto system voice > customize...).