Previously I had posted about spotting your train on Google maps using and later from the official source. I was recently traveling and used another mobile website by National Train Enquiry System by Indian Railways. I used the  following mobile site in my Android mobile browser through out the journey and found that it was getting updated very frequently, some times after couple of minutes after leaving a station , which is the least lag I have ever seen in any Indian railway related site. Moreover you don't have to really wait till an official  stoppage comes to know how much late the train is running. It updates the passing by the stations ( even if it is a small one) also which comes very frequent.