It has been notoriously difficult to make a living from selling content on the internet. But SEOmoz seem to have found the magic formular and are on course to generate a whopping $1,289,760 in the first full twelve months alone. read more here: http://dfinitive.com/blog/seo/seomoz-well-on-their-way-to-1-million-from-selling-content/
That's some good amount of profit to be made by content writing which takes a lot of effort as every time an article is written it has to be different and unique in its approach and that is an hectic job.