Read and write in tamil

1) for type online http://www.google.com/transliterate/  

2) Choose Tamil for chrome https://chrome.google.com/webstore/detail/dooacmfhdikjfklbmejepfcjblnfjnhp#

3) Install the local window client  http://software.nhm.in/products/writer

For Firefox use addon https://addons.mozilla.org/en-us/firefox/addon/tamilvisai-tamilkey/

for Chrome Use this add on https://chrome.google.com/webstore/detail/gafpeaoljjcahihccmjpkmijdlmocnjl

Hope this works