@lonelygod - If you want to see Tamil movies online for free I would recommend checking out some of the YouTube Tamil movies that are available. YouTube has a pretty good selection of films, and they generally don't block or pull down foreign films, unlike with the Hollywood blockbusters.
Now the problem is knowing what to look for when you get on YouTube. I would recommend trying to find a forum that specializes in Indian movies. Thiraipadam has a great list of Tamil movies and with such a comprehensive database at your fingers I am sure you'll find hours of films to watch.