Vikram Joshi, IIT, has a TTS extension:
He says: "Text to Voice' or 'Text to Speech' is one of the coolest add-ons. It gives Firefox the power of speech. Select text, click the button on the bottom right and this add-on speaks the selected text for you. Isn't it brilliant? Audio is downloadable."
Is an extension using Tamil TTS code of prof. A. Ganesan Ramakrishnan, IISc available?
Thanks,
N. Ganesan