The Dataverse Network Project is an operational, open-source, digital library to enable the sharing of quantitative research data. The IQSS Dataverse Network is available for public use for searching across many publicly archived sources of data.  Many of the data are available for free download, while others require institutional subscriptions.

(The HMDC numeric data services unit maintains access to numerous restricted or fee-based data collections for use within the Harvard community).

Scholars, programs, archives, and institutes can set up their own Dataverse's to make their data more widely accessible and cited.

Link(s):

http://dvn.iq.harvard.edu/dvn/

http://thedata.org/