Indeed.com is not just good for reviewing job listings. They have some really cool analytics tools as well, including this one (http://www.indeed.com/jobtrends) – which enables you to look at job trends by plugging in a key word or phrase. For example, type in “Twitter” and watch the line graph shoot off the page. Conversely, type in “COBOL Programming” and see the line zig zag downward.
This is a great way to see what kind of keywords show up most in resumes, and therefore, what keywords you should think about having in your resume and what skills you should have in your repertoire!