Postal Index Number is a post office numbering system in India; a PIN code on the consignment, at the end of address helps the post office staff to easily organize the mails and hence enables a faster service. Earlier it was used only by post offices but these days even the courier companies demand the PIN code number.
Here is an online resource, WhereInCity, which can help you to get PIN Code number of any place in India easily.
Here you can either use the search engine like interface, using it you can search either for a place to get its PIN Code or you can search for a PIN Code to get the location of it, or you can browse through the states, and later on the basis of district and other entities like tehsils etc.
So go ahead and use this tool to find PIN Codes of any place in India, and speed up your snail mails. Visit WhereInCity
Related : You can also try Try Pincode search @ Maps of India