Over the last couple of months there have been a spate of online book shops that have opened up. FlipKart, Pustak and a1books. I have used FirstandSecond, fabmall (now Indiaplaza) Rediff and LandMarkontheNet in the past, but have been blown away by the ease of search and ordering at Flipkart, not to mention the great discounts and free shipping that they offer.
Yet to order any books from Pustak and a1books though!
This proliferation of online book stores is a welcome move, Amazon, if and when they chose to come to India would be too late and will have tough competition