Sortfolio uses Amazon’s Mechanical Turk (“a global, on-demand, 24×7 workforce”) to make sure no NSFW images make it into the galleries. It’s pretty amazing how quickly the processing happens. A visitor uploads an image. Above is the review screen the “turks” see in order to approve/reject. Then the image goes live. The whole thing takes just a few seconds and costs us only a penny per image.
Full disclosure: Amazon’s Jeff Bezos is an investor in 37signals.