Here are some of the best resources on the net regarding your preparation for the civil services exam. If you are aware of some more useful resources please inform us about it and we will put it here for our other friends

UPSC Portal - Official UPSC Site

New Scientist

Competition Success Review Portal

Competition Master Portal

General Studies Info Bits

Bulletin Board for IAS

Saidai Duraisamy’s Manidha Naeyam I.A.S & I.P.S Free Coaching centre

Tamil Nadu Public Service Commission (TNPSC)

Kerala Public Service Commission

Andhra Pradesh Public Service Commission

Karnataka Public Service Commission

Himachal Pradesh Public Service Commission

Orissa Public Service Commission

Sikkim Public Service Commission

Jammu and Kashmir Public Service Commission

Punjab Public Service Commission

Maharashtra Public Service Commission

Gujarat Public Service Commission

Madhya Pradesh Public Service Commission

Rajasthan Public Service Commission

Uttar Pradesh Public Service Commission