One of the first ways I earned money online was posting on forums. There are many sites available that allows you to get paid by just posting on forums. A lot of sites will actually pay you good money to post on forums. It will not make you rich, but it will put money in your pocket.
I also have been making some extra money by signing up for paid social networks. You can actually make good money just by using the site daily believe it or not. All you have to do is just log in and do the same thing you would do on any other social network.
The last two things that I do is get paid to sites and surveys. I started earning money the same day on several different survey sites.