The Riley Guide - More than just a comprehensive guide to job listings on the web, this site also contains job search and networking advice, salary guides, and information helping you to better research potential employers.
Occupational Outlook Handbook/BLS - This website contains information about many different kinds of careers.
Idealist.org - A great job search tool but also a way to research organizations. You can also find articles and insights on careers in the non-profit sector.
Vault Online Career Library - Provides excellent career and industry information. Many Vault Guides and Company Profiles are available for FREE to download here.
WetFeet.com - Research careers and industries, get job search advice, and read employment trend information. FREE WetFeet insider guides to various careers, companies and industries are available here.
Wall Street Journal Careers - A fabulous site for career trend articles, job search advice, salary information, and other career-related information.
Salary.com - Useful place to start when you need information about salaries.