Macrodata Guide – An International Social Science Resource (developed by NSD)
http://www.nsd.uib.no/macrodataguide/

Pippa Norris Datasets on Democracy
http://ksghome.harvard.edu/~pnorris/Data/Data.htm

Quality of Government Dataset
http://www.qog.pol.gu.se/

Lijphart Elections Archive
http://dodgson.ucsd.edu/lij/

Slovak Election Data Project
http://sites.google.com/site/marekhlavac/slovak_election_data_project

Statistical and Data Archives on IPSA portal
http://ipsaportal.unina.it/?cat=16