Whether for high school students or adults, you can monetize your expertise by teaching people with less experience or knowledge than you in that subject area. You can work with an established group like Kaplan for, say, SAT tutoring, or you could try hanging out your own shingle and making your services known either to students, parents and schools in your community. If you are targeting adults, you can create your own website or list your services with adult tutoring companies.
While we all have some extra time, it often doesn't feel like it. But it also doesn't take too much effort to make some extra dough on the side. We're not talking about millions upon millions here -- we're mostly talking about doing small, bite-sized projects to generate some fast cash. And depending on your skill set, you could easily make a few hundred dollars or even a few extra thousand per month.
Utilize websites like Payscale.com, Salary.com, and free salary guides from Robert Half and Randstad to find out what a competitive salary might be for someone with your expertise and education in your area. Document everything that you have accomplished at work in the past year and present it to your employer. When you are making an honest case for yourself instead of demanding a raise, your employer will at least consider your request.