The Harris Poll is the longest running proprietary survey of public opinion in the world. In February 2014, The Harris Poll was acquired by Nielsen.
Also, use the Harris Vault to search over 40 years of data.

Collection of data on the economics and business of U.S. pro sports leagues. Also, some college football, World Football (including Major League Soccer), and other general sports-related data.

From the Statistics in Sports Section of the American Statistical Association, a listing of online data resources and online sports statistics forums for several sports.