I've had a few recent sales on Fine Art America but I want to warn anyone who thinks its easy to sell artwork online - its not!
Its easy to OFFER your artwork online but actually becoming noticed among the hundreds of thousands of pieces of artwork (ranging from amazing to hohum) on these sites it very difficult. Every single day over 2,000 new pieces - paintings, photographs, drawings etc, are added to sites such as Fine Art America.
In my old economics class in college I recall the concept of "barriers to entry" - that is a market that has a hard barrier like producing steel (you need a large expensive factory) is going to have few competitors. But something like a lemon-aid stand which anyone could open is going to have fierce competition.
Print on demand art sites have little or no barrier to entry. The offerings are not even reviewed for quality. So as a result you get everyone from some posting their vacation photos to offerings from established artists.
So if you want to sell your artwork on Fine Art America, Red Bubble or Society 6, realize that it not going to sell on its own. You still have to social media the heck out of it in order for it to be seen.