Corporate Predators
http://www.corporatepredators.org/
Web site of the book Corporate Predators: The Hunt for MegaProfits and the Attack on Democracy, by "Focus on the Corporation" columnists Russell Mokhiber and Robert Weissman. Quite an eye-opener. Includes excerpts from the book, a list of the top 100 corporate criminals, recent columns by the authors, and more.
McSpotlight
http://www.mcspotlight.org/
This site started out providing updates on the "McLibel" case in England, where McDonalds sued two environmental activists who distributed anti-McDonalds leaflets for libel. That case is over, but there's much more to the site, including discussion forums, a gallery of McDonalds "subvertisements", and more...
Multinational Monitor
http://multinationalmonitor.org/
A print magazine devoted to keeping tabs on the doings of multinationals. Complete text of many back issues online.
The People-Centred Development Forum
http://www.pcdf.org/
Originally hosted by the International Institute for Sustainable Development but now on its own, this site is dedicated to "the possibility of creating a post-corporate, post-capitalist world of living democracies, mindful market economies, and authentic cultures." Contains a number of interesting articles, and samples of several books by its president, David C. Korten - the classic When Corporations Rule the World, and its follow-ups, The Post-Corporate World, Globalizing Civil Society, and Getting to the 21st Century.