People often ask me how I became the Physical Therapy Guide on About.com. A few years ago, I had a patient who is a guide, and she told me about writing for About.com and how much fun she has doing it. She said it was great because she worked when she wanted to, and she got to choose the content that she provided to her site.
I logged onto About.com and saw that the Physical Therapy Guide position was available, so I submitted a writing sample. A few weeks later, I was contacted to go through the "interview" process of submitting more samples of my work. I made it through and became your guide. Easy peasy, lemon squeezy.
If you are an expert in your field and are passionate about writing, perhaps you can write for About.com too. Simply log onto About.com and scroll to the bottom and click the link, "Write for About." Good luck!