It used to be that in order to work online you had to have mad skills with a computer. While that does help, there a jobs now where the average user can earn a little extra income. I will list a few I have experience with.
-Amazon Mechanical Turk (skill level: 3/5)
Amazon's "Artificial Artificial Intelligence", In this job you are matched with tasks to perform based on your level of expertise. The longer you work for them the more they allow you to do. The tasks are menial jobs that are too easy for the company to be bothered with but require human intelligence and thus cannot be shucked off to a CPU. The harder the job, the better it pays. Sounds pretty boring but some of the tasks are entertaining and best of all you can PICK the ones that interest you and ignore the others. Also many companies will reward good work with a bonus payment. I once received such a payment because the reviewer thought that my answer to a question was funny! There are universities that post their psychological studies for Turks to complete for their research that tend to pay well as well as websites that post topics to write articles for. You can request payment from Amazon at any time so long as you have earned more than $5.00 and have it deposited into any checking account you have on file. Or if you don't have a account to send it to you can use the balance to shop on Amazon's site. For books, of course.
-ChaCha (Skill Level 1/5-3/5)
If you've ever wanted to ask a stranger "Should I wear a blue shirt or a red shirt today?" You've probably used ChaCha (and were probably told to wear the red unless you work for a guy named Jean Luc Picard). ChaCha is a text-based service that sends answers from real live people to you. In order to get so many real people, ChaCha is willing to outsource a little. You can work for ChaCha as a Guide as freelance work. (i.e. you work for them but you aren't an employee, you're not responsible to them nor they to you). There are different jobs to choose from: