Marketing and Demographics
Gallup makes many of its polls available online:
Gallup Polls
Use Nielson research to find out demographics such as income, marketing segments, and more:
PRIZM My Best Segments from Nielson (formerly Claritas)
Demographic information about the U. S. is also available from the U. S. Bureau of Labor Statistics:
Labor Force Statistics
From the U. S. Small Business Administration:
Statistics for Specific Industries
Global information from the United Nations:
http://data.un.org/
Investments and Stock Market
SIFMA (Securities Industry and Financial Markets Association)
20th Century American Leaders Database: From the Harvard Business School, a large collection of names, industries, and historical eras
BRASS Best of Business Resources (from the American Library Association)