These commercial sites have job listings, some internships, information on employers, on-line job fairs, advice on job hunting, and places where you can post your resume for free. There are many others.
A wage determination (WD) is a listing of wage rates and fringe benefit rates for each labor category of workers which the U.S. department of labor has determined to be prevailing in a given area.
Vocational & Career Collection is designed for vocational and technical libraries servicing high schools, community colleges, trade institutions and the general public. This collection provides full text coverage for 400 trade and industry-related periodicals.
Often, there will be many titles of jobs in a field. These websites help you identify those titles which are relevant to your skills and the field in which you are seeking a position.