Since Google added street and road maps for India back on December 19th, 2006 new mashups are starting to emerge to help residents do everything from using public transit to finding a home..
Google Map of Mumbai Metro Rail System:
Description from site: "..Mumbai (formerly Bombay, approx. 10 million inh.) currently has four rail corridors exclusive to the mass transit system (with separate tracks) totalling 149 Km." This Google Map created by Hiren Pathak plots the station stops and shows colour coded lines for the Thane Vashi, Western, Central and Harbor Metro Lines.
Housing Maps Mashup for Bangalore:
FindMyGhar is, to the best of my knowledge, the first Google Maps housing mashup for India. A help page describes how to use the site to find homes in Bangalore, while the FindMyGhar Blog will keep you up to date on changes and features to the site.
India's Top 10 Colleges:
This is a mashup of the top 10 Engineering and Medical Colleges that are presented on IndiaEducation.info.
See more Google Maps mashups for India in this recent post.