I have really enjoyed the navigator site developed by IITB . This site was developed by Prof Abhiram Rande and other Masters students from CSE dept of IITB. Really great effort. They have developed using OpenLayers and the bus stops layer is generated using MapServer.
As a transportation Engineer, am not sure whether any routing engine is used behind the scene or not. Generally developing routing application for Indian conditions is very tough. Anyways, Best wishes to team who developed this.