The Internet is a source of free survey information. However, much of the information is unreliable. The best way to determine reliability is to evaluate how the data was collected. Many rely on voluntary disclosure of salary information from readers. These surveys generally don't represent an valid cross-section of employees.
Headhunters often disclose salary statistics, based on the individuals that they place.
Below is a list of web sites that appear to have more reliable data than most on the Internet. For the 1999 survey, data on compensation is gathered from among more than 1400 employers of information systems professionals, nationwide, including corporations of all sizes, in every industry group, and from every U.S. region. A total of 681 usable returns had were submitted. Also included is salary information from several Asia-Pacific countries. Finally, the following two sites include links to numerous web sites that contain a wide variety of salary surveys.