We all know the popular careers available to us-doctor, lawyer, teacher, computer engineer, police officer, store owner, etc. If you feel uninspired by the typical choices, know that there are thousands of unusual jobs you might not have heard about, hidden, perhaps, in the Bureau of Labor Statistics' Occupational Handbook. Mashable has a list of six dream jobs that pay well (panda caretaker! Chocolate inspector!), Thought Catalog highlights 10 more (sex toy testers?!), and Chron lists a couple of others (along with related articles like "Unusual careers with animals" and "unusual accounting careers").
If there's a career you're interested in, you might also check to see if any companies or people in that line of work would let you shadow them for a few days to see what it's really like.
Well, you say, what if you don't know what you're good at or even what you're interested in? Career assessment tests in college or even high school help narrow down a field (perhaps with the Myers-Briggs personality index), but if it's been a while since you took those tests, there are other kinds of assessment tests you can take. This one from Rasmussen College matches your self-reported skills and interests with potential jobs. (And they also have a salary and job growth interactive chart.) For potential programmers, Switch recommends a coding career based on your preferences. About.com's Job Search site has a collection of other career tests.
You can also find a career that fits your motivational focus with this assessment test.