1 Salary Expert
The site's self-description " SalaryExpert reports are used by thousands of people to help them better understand their "worth" in the employment marketplace. Our reports not only factor in salary information, but also benefits and "cost-of-living", thereby providing the most comprehensive, yet free, information available on the Web."  This service is free for the basic report.  Gives zip code based wage survey information.  Also provides DOT description of job duties.

2 Occupational Employment and Wage Estimates
This site provides employment and wage estimates information by occupation. The information is available at the national, state, and metropolitan area level. It is further categorized under managerial, professional, sales, clerical, service, agricultural, and production. For each occupation, it provides the OES code, occupation title, definition, employment level, mean wages, and median wages. From the Bureau of Labor Statistics. http://stats.bls.gov/oes/oes_data.htm

3 America's Career InfoNet
Occupational and employment information, including overviews of the job market for the U.S. and for all fifty states. Profiles hundreds of specific occupations, including detailed salary and wages information by state and county from the Bureau of Labor Statistics. http://www.acinet.org/acinet/