Finding demographic information (age, sex, income, etc.) and lifestyle information (media exposure, shopping habits, decision dynamics within a family, etc.) about prospective customers is essential to getting the word out to customers in lucrative market segments at the lowest possible cost.
Mediamark (US data) and Mintel (US and some International data) are the best places to get a comprehensive look at customers within specific market segments. Passport GMID (US and International data) features separate product reports and consumer reports by country.
Mintel . Offers market research reports covering US and International markets. Each report combines data & analysis of the competitive landscape, market-share analysis and consumer profiles. Complex demographic issues are broken into easy-to-understand sections, explaining consumer behavior and demonstrating the structure of the market.
(Passport Global Market Information Database) Market analysis for companies in this database includes links to global and country reports and key competitor reports, providing context for company operations. Focused mostly on prominent companies with international operations (e.g. Microsoft, Yum Brands, and L'Oreal), this database is reliable, complete, detailed, and up to date.
Consumer Behavior This annual report by Richard K. Miller and Associates on trends and patterns in American consumer markets (available via Business Source Complete) has lots of good information about buyer behavior and how to influence various demographic groups.