Career information compiled by the US Dept of Labor or other career organizations. Several sites describe all types of careers or interview someone "doing" that job/career.
An Informational Interview is a meeting with someone who works in the career field in which you are interested. The purpose is not to obtain a job but to ask questions and learn as much as possible about the nature of the work. Source: Career Development for Health Professionals by L. Haroun.
These sites offer some good descriptions of various health careers.