So far I've been doing quite alright with Zazzle.
You can make all kinds of products there.
Fotolia is ok as well. I have a tad of a problem to get new shots in lately though.
I sold a few cards on Greeting Card Universe, but their servers or programming are a killer for my slow Internet. Can't work on there to make new stuff, cause it's too slow for me.
Redbubble is a success for quite a few of my artsy friends, not for me yet though
I might give QOOP a try in the near future.
Also Blurb and LuLu for picture books, but all in it's own time.
I had a pro account at SmugMug for a while. I loved the Site but had no Sales.