Budge, Keenan, and Woldendorp
http://einstein.library.emory.edu/pub/ICPSR/Electoral_Politics/budge/
Data on national election results and governing coalitions in post-WWII Western Europe, up to 1995. Please refer to the codebook in order to understand the Excel spreadsheet that contains the data.
Comparative Political Data Sets (CPDS)
http://www.ipw.unibe.ch/content/team/klaus_armingeon/comparative_political_data_sets/index_ger.html
The CPDS were produced by scholars at the University of Berne. They focus on OECD countries and on post-communist countries and contain much data on the structure of political institutions, as well as data on demographics, electoral results, and ideological compositions of governments. There are also variables for female participation in parliament. Please note the preferred citation format.
Comparative Study of Electoral Systems
http://www.cses.org
This site contains data and documentation for a cross-national collection of election studies. The CSES combines microdata on respondents with data at different levels of geography (i.e. data on respondents' electoral districts and on the political institutions of their countries) and focuses on themes such as how macro-level variables such as electoral systems affect political attitudes.
Database of Political Institutions
http://go.worldbank.org/2EAGGLRZ40
This database was put together in part by Phillip Keefer at the World Bank and provides data on the political institutions and structures of different countries in the world from 1975 to 2009. Additional documentation are also available here. Please note the authors' preferred format for citing their data.
Elections in Western Europe Since 1815 (Emory's Data Center)
http://einstein.library.emory.edu/euroelect
Emory's Electronic Data Center provides instant access to Daniel Caramani's detailed collection of European election results. Election results are available in a variety of different statistical formats for easy access and anlaysis.