zip code
we can write a YQL as [ select centroid from geo.places where text='Enter some pin code here'].Yahoo encourages us to use YQL in commercial applications. (http://developer.yahoo.com/yql/faq/ )Most number of allowed queries as compared to all other options i.e. 20,000 calls/hour/IP and 100,000 calls/day/key. (see http://developer.yahoo.com/yql/faq/ ), Support available for YQL is quite good, see the links.