When you receive a job offer, there is more to evaluate than just salary. Think about the position, the organization, your supervisor, job location and cost of living, benefits, and any other personal or professional factors.
You should gather information about salary averages prior to an interview, but if you are deciding whether to negotiate or not use the following resources to guide you:
NACE Salary Calculator - The National Association of Colleges and Employers (NACE) provides this salary survey data resource. This information is based on a national study of salaries in various career fields.
UW-Whitewater Salary Survey
Glassdoor.com - Search salaries and compensation information for various companies provided by current and former employees.
Salary.com - This resource provides salary averages for your field and in your geographic area of interest.