Need some extra cash but don't want to leave the comfort of your home? Luckily, it's the 21st century and online opportunities abound. You can often telecommute for your company at least once a week, or pick up extra work from other sources. Get creative, and keep an eye on work-at-home message boards for new options. Here's how to earn extra money at home on a computer.

1. Online tutoring Online tutoring Use your existing skills or job experience to get an online job. For example, medical doctors, lawyers, tutors and other experts can earn money by answering users' questions on the Just Answer website.

2. Customer Service Customer Service Check out LiveOps. With this company, you receive calls from people contacting any number of businesses. You have a written script to follow and are paid by the minute and extra for any add-ons you sell (such as bread sticks when someone orders a pizza). You need to have a fast internet connection and certain software capabilities, but once you are set up, you can earn $10-$30 an hour, according to some LiveOps contractors.

3. Freelance writing Freelance writing Become a freelance online writer. Write for sites such as eHow, as well as private clients that you can find through sites such as Rent-A-Coder and Elance.

4. Graphic design Graphic design Use your graphic design skills to design web site graphics, photo greeting cards, and business materials for companies. Advertise yourself locally (try CraigsList), at copy stores and on eBay.

5. Try publishing and selling your own crafts, written works and graphic arts on site like Lulu (best for books and eBooks) Etsy (best for handcrafts) and Cafe Press (perfect for graphic designs).

6. Build your own website. Think of something you enjoy or are good at. What skills or knowledge do you have to share with others? See resources, below, for a great site that walks you through the process of building a profitable niche site.

7. Network online Network online Join a forum, such as the one at WAHM.com, to stay on top of job ideas and opportunities. You'll learn new strategies for short-term projects and long term money-making ideas, which combined will enable you to earn extra money at home on a computer.

8. Online photo selling Online photo selling Sell digital photographs online to earn extra money at home on the computer. Take good photographs, bringing your camera everywhere to get a variety of shots. See link under resources, below, for a great source of information on making money with digital photography.