BBC News - In Depth: Inside Europe - Ongoing collection of news and views plus background briefings, country profiles, history and online audio programmes. Includes issues of enlargement and an EU constitution.
Campaign for an Independent Britain (CIB) - Coalition group which seeks the UK's withdrawal from the EU, and specifically the repeal of the European Communities Act of 1972 under which EU directives take precedence over UK law.
Democracy Movement - A non-party campaign to keep the pound and stop the "European Superstate"; formed from Sir James Goldsmith's Referendum Party and the Euro Information Campaign.
EU Referendum - Blog that looks at the issues related to the UK's position in Europe and the world
European Movement UK - All-party movement campaigning for the European Union to become more democratic and effective, and for Britain to play a full role within it.
Euroseptic.co.uk - Eurosceptic humour, graphics and icons, and merchandise.
Guardian Unlimited Special Report: European Union - Ongoing coverage with news, comment and analysis about the European Union itself and its issues, policies and future. Includes links to official documents, European government and media sites.
I Want A Referendum - Campaigning for a vote on the EU reform treaty, arguing that it is substantially the same as the 2005 treaty on which a referendum was promised.