List of websites where you can buy Tamil books online:
1. NHM – Kizhakku Padhippagam – Online shop of the leading Tamil publication house Kizhakku Padhippagam (கிழக்குப் பதிப்பகம் ). Offers free shipping within India if you buy for more than INR 250. It’s the only Tamil publication whose books are available in Amazon.com . I have ordered books from theme and found their service good.
2. Flipkart – Tamil books collection from India’s leading online books store. I have bought from them many times and they continue to amaze me. They update and deliver you with a precision of dropping a nuclear bomb !
5. Udumalai – A friend of mine says he got his books after 10 days from ordering with lot of trouble. So, watch out !
8. Viruba.com – A database for Tamil books.