Our declared objective is to promote the Open Access initiatives. One of the most promising ways to distribute the research output of the universities and research centers is to deposit scientific papers and related material at institutional or disciplinary repositories.

Using as basis the data from the Registry of Open Access Repositories (ROAR) and The Directory of Open Access Repositories (OpendOAR) we have compiled a list of repositories with the following conditions:

- Only repositories with an autonomous web domain or subdomain are included:

repository.xxx.zz (YES)

www.xxx.zz/repository (NO)

- Those repositories consisting only of one or several electronic journals (journal' portals), or devoted to non scientific papers or focusing in archival material are excluded.

With the aim to improve visibility of repositories and good practices in their web publication we have extracted the following quantitative web indicators from the most important search engines. The methodology is similar, but not exactly the same, to those use in our other Rankings:

Size (S). Number of pages recovered from the four largest engines: Google, Yahoo, Live Search and Exalead.
Visibility (V). The total number of unique external links received (inlinks) by a site can be only confidently obtained from Yahoo Search and Exalead.
Rich Files (R). Only the number of text files in Acrobat format (.pdf) extracted from Google and Yahoo are considered.
Scholar (Sc). Using Google Scholar database we calculate the mean of the normalised total number of papers and those (recent papers) published between 2001 and 2008.

The four ranks were combined according to a formula where each one has a different weight but maintain the ratio 1:1 between activity (size sensu lato) and impact (visibility)

Any remark regarding addition or deletion of academic repositories is welcomed, as well as any comments or suggestions that will help us to improve the Ranking.