Disinfopedia This is a nice Wiki that allows users to collaborate on a directory of those who try to influence public opinion. It has a definite leftist bent (it is ran by the Center for Media & Democracy) but left wing organizations attempting to manipulate public opinion are also covered. The powers that be are also quick to kill spam and vandal edits.
From the site:
Welcome to Disinfopedia, a collaborative project to produce a directory of public relations firms, think tanks, industry-funded organizations and industry-friendly experts that work to influence public opinion and public policy on behalf of corporations, governments and special interests. Sponsored by the Center for Media and Democracy, the Disinfopedia was started in February 2003 and contributors are now working on 5075 articles.