ELPRG is a network of younger researchers
with a common interest in legislative politics in the European Union (EU). The aim of the research group is to further our understanding of EU legislative politics, i.e. of the interaction between the EU institutions in the legislative decision-making processes
Their website has an excellent link to voting data, public opinion and political parties and there is a good overview of recent publications on legislative/voting behaviour and related topics. Unfortunately, they seemed to have stopped updating the website in 2012. The coordinators are Anne Rasmussen (Leiden) and Andreas Warntjen (Twente).