If you have graphic design or web skills then you can pretty much start your own business with tools you probably already have at your disposal - only finding work would cause you start-up pain. I do work on the side, in addition to my full time position - i'd never give up the full time because of the constant income. There's times when i earn more (and do less to get it) doing freelance than my 'main' job, but it isn't always the case.