The Webometrics Ranking of World Universities has created a new ranking of Repositories http://www.webometrics.info/top200_rep.asp.
From that first three are subject based repositories(arxiv, Repec, E-lis)because these are subject based and deposited by all over the world.
From the 200, three are from india, may be in 3 or 4 year we have more in the rank but still we called its a good achievement.
These three are
IISc, Banglore in 46
Indian Statistical institute in 67
Openmed National Informatics center 110
but there few other indian repositories they have rich in collection but not came in list.