Google has now come up with a splendid online tool to get text in Tamil while typing in romanized form (type arun, aarthi etc to get the same words in Tamil) please visit
The converted Tamil word shows up every type you type the space at the end. If the word is not displayed correctly, you can correct it - simply select the word and use right click to get a choice of words to choose. Try it. You can then send emails out in Tamil Unicode. simply copy-paste the text to a standard email message window.
i have been using the transliteration software by cadgraff for some time. typed more than half a million words. the result is my english typing has gone for a six. you start thinking about words in a phoenetic way.
two things about transliteration
it will create a lot more writers in tamil two it will make extinct the traditional tamil typing.
This is a neat solution. I used to have problems reading tsc emails from agathiyar and other groups to unicode. Used an online conversion tool from adhiyaman