Think Tanks

Here are some think-tank directories, courtesy of Resource Shelf
Hillwatch.com: Think Tanks ("A directory of Canadian and International Think Tanks")
KSG Directory of Think Tanks (Kennedy School of Government, Harvard University)
NIRA's World Directory of Think Tanks (National Institute for Research Advancement in Japan. Hard copies of the directory are issued every three years. The 2002 edition is online here.) Political Resources: Think Tanks (Project VoteSmart)
Political Resources: Think Tanks (University of Michigan Documents Center)
Worldpress.org: Think Tanks and N.G.O.s