European Environment Agency
The website of the EEA has briefings, reports (including country reports), and indicators.

European Commission: Environment
News and policy of the European Union.

European Environmental Bureau
The EEB is an umbrella organization made up of European environmental NGOs.

Institute for European Environmental Policy
The IEEP is a research organization focusing on environmental and sustainable development policy of the European Union. Many publications are available for download.

The Regional Environmental Center for Central and Eastern Europe
A nonprofit organization that focusses on environmental problems in Central and Eastern Europe. Their website houses project descriptions and publications as well as links to the websites of their offices in individual countries.