This study rated the ACLU as slightly conservitive (which is accurate),

"Center for Responsive Politics, a group whose primary purpose is the maintenance of databases on political contributions, scored a 66.9, making it highly "liberal."

and

"Center for Strategic and Budgetary Assessments, a defense policy think tank whose board of directors is currently chaired by former Representative Dave McCurdy (D-OK), scored a 33.9, making it more "conservative" than AEI and than the National Taxpayers Union."