All these India's domestic flights now have online booking system as well as they all have their specials deals every now and then.
The List of domestic flights are
Here is the list of domestic flight carriers
AIR DECCAN is Indias first low cost airline which is the business unit of Deccan Aviation Private Limited. In India, this aircraft has already proven to be a highly successful one, both for its efficiency and cost effectiveness. It is presently being used by both, Indian Airlines and Jet Airways. ABOUT AIR DECCAN AIRLINE
SpiceJet, the latest entrant on the low cost carrier scene commenced services on May 23. The airline has attracted a large number of passengers with its 'Red Hot Special Fares' offering tickets as low as Rs 99. The airline connects six destinations - New Delhi, Mumbai, Goa, Bangalore, Pune and Ahmedabad
*new* GoAir (http://www.goair.in/)
~ no differentiation in fares between NRI/tourists and residents
~ flying between Ahmedabad, Mumbai, Coimbatore ad Goa
~ 10,000 Free Tickets Per Month
Air Sahara
It is a privately owned airline operating scheduled services connecting all metropolitan centres in India. The airline also provides helicopters which are available for charter services and aerial photography. (http://www.airsahara.net)
Jet Airways is a full-service scheduled airline based in Mumbai, India serving domestic and international routes. The airline operates over 320 flights to 44 destinations across the country and 6 overseas
And the last two are Kingfisher and Indian Airlines.