Being from Iran, I'm particularly interested in Persian language.
Google have had a Persian transliterate tool for some time (http://www.google.com/transliterate/persian).
Much earlier than Google, http://www.behnevis.com/ was out by a couple students which is a pretty active and feature-rich project. I would recommend it to anybody over Google’s transliterate tool but I would love to see Microsoft ship one under Maren or get Behnevis integrated into Maren *wishful thinking*.