Careersinthemilitary.com is useful for finding out about occupations in the United States Army, Navy, Air Force, Marine Corps, and Coast Guard.  It provides information about job duties, work environment, training requirements, career paths, and job opportunities. 

The Occupational Outlook Handbook (OOH) is designed to provide valuable assistance to individuals making decisions about their future work lives.  Revised every two years, the OOH describes what workers do on the job, working conditions, the training and education needed, earnings, and expected job prospects in a wide range of occupations. 

O*NET OnLine, the Occupational Information Network, is an online database that contains comprehensive information on job requirements and worker skills and abilities.