there are so many ways to earn money online. Just do what you like..if you like selling why don't you create an establish site and try to sell it..actually I earn money from selling site and forum posting in some paid to post forum
Blogging This one of the best ways to make money online. Just start a blog having relevant content, news and latest buzz. Sign for Google AdSense, to get posted with ads. Every time the ad gets clicked, it will fetch you bucks. http://www.myeasyonlinepay.com
You can also make money through online internet marketing. I got a superclass training on online business and I love the results that I am getting. http://www.theinternetmarketingsuperclass.com/superclasstraining. It really works.
Find something you want to promote and stick with it, look for ways to "rinse and repeat," do the work to set things up and get money coming in, then start another project to do the same thing while the first one continues to generate revenue. And as googlecrawl mentioned, you can always sell the site or online property if you need a larger sum of quick cash.