There's a great amount of freely available data from various governmental agencies that provide an overview of various careers. From salary data to trends and projections, these resources can give you a high-level analysis of a career of interest.
The OOH provides info on hundreds of different careers including salary data, educational requirements, outlook information, work environments, and more!
Provides data and info on over 900 different careers/occupations including what people do in each career, a quick video on that career, projected employment, salary data, and more!