CareerOneStop - Sponsored by the US Department of Labor, Employment and Training Administration. Learn about typical wages and employment trends across occupations and industries.
Glassdoor - Provides useful budgeting tools to help you estimate your living expenses and salary needs.
Salary.com - Salary information with search by over 60 career categories and by location. Also provides information about compensation, salary/benefits negotiation, and an advice column.
What Can I Do With a Major In...? - Employment and salary information for recent UC Berkeley graduates, from the Career Center's annual survey.