Online writting is an art.If you are having the art and skill, you can publish articles or stories on internet.Now, people depend search engines such as Google,Yahoo,Bing etc for Reviews for buying a product or service.It helps them to get knowledge about specific areas.You can start a blog and earn income from advertising, if you have patience for long term gain.Otherwise,start with popular freelance writting websites.I think,following sites are already doing great job in this field.
Over 12.5 lac articles published in Hubpages till now.You can write about any topic and earn as per the popularity of the Post.They will share the advertisement income of your page.Hubpages are conducting contests also.For more details,visit: http://hubpages.com/
This site is another free platform for writers.You can share story,opinion or interest with readers at
How to articles about various topics are the highlights of http://www.ehow.com/
d. Yahoo!Contributor network
This popular site allows people to write and share photos or videos for various yahoo sites.Visit http://contributor.yahoo.com/signup/ for details.