Here is a complete list of services offered by the Indian Railways which you can find on the official site (http://www.indianrail.gov.in/) of Indian Railways. An overview of each service is mentioned here.
PNR Status: The most frequently used service by every passenger of the railways. The PNR Status service is for checking the berth confirmation.
Trains Between important Stations: Commuters can check the running trains between two stations and can plan their journey. Return Journey trains can also be checked here.
Seat Availability: Are you planning for journey. Then use the berth availability feature to know whether there are any seats available for booking in a train.
Fare Enquiry: Know the fare of the train and also check for concession availability in the train.
Mobile Ticketing Services: This service is only available in Mumbai and Chennai. Passengers can book a ticket through the mobile application. Upon booking ticket will be delivered to the mobile application.
Train Schedule: Just by entering the train number / train name, users can get the train schedule details. Schedule information like train halting stations, arrival time and departure time will be provided.
NTES: The national train enquiry system online service which provides the live location of a running train. This is also one of the widely used service and passenger use this service frequently for checking the train delay and location.
SMS Service: Passengers can check pnr status of a ticket by sending an sms to 139. Confirmed train ticket can also be cancelled by sending the ticket details as an sms to 139.
Current Booking Availability: Did you planned your travel just now and want to travel right away. Then this service is for you. Check for any seats availability using this service.
Apart from these services, there some features which are used rarely. They are train type information, view codes, trains at glance and rules. Did I missed any important service of Indian Railways, the comment here.