IndiaRail Info is an interesting Google Maps mashup that helps you visualize the current geographical location of any train in India. Just type train name or train number and check its exact location on the map.

India Rail Info has a database of all trains and railway stations in India

For example, the Bandra Garib Rath Express (2910) has crossed Kota junction at 8:23pm IST. Unfortunately this site does not extrapolate this data to guess the location between two junctions, so the train is still shown at Kota. Thanks Info-Madness.