I read a paper written by a French researcher saying people's main ways of online laundering money is through mediums like Freelancer.com & In-Game money.
I wondered how the hell that would work? Surely they would need to put their cash into a system to start it off anyway?
The main way laundering is done is to exaggerate the legal work done to encompass some of the illegal money. For freelancing, say you put up yourself as a graphic designer. Some anonymous person, who is also you, pays you to make a dank logo. You don't need to actually do this, just send the money to yourself and say you did. Of course, it's dangerous and more complicated than I described, please do more research if you plan on laundering money.