All user-contributed, all the time (almost)

I’ve been fascinated for the past couple of years with businesses that rely on user-contributed content (UCC) for substantial inputs to production. It is sometimes jokingly referred to as the “Tom Sawyer business model”: get your friends to whitewash the fence for you, without paying them (in fact, they paid Tom quite handsomely, including “a key that wouldn’t unlock anything, a fragment of chalk…and a dead rat on a string”). Tom Sawyer's Whitewash
Randall Stross writes in today’s New York Times about two fairly well-known businesses that have nearly perfected the art: Plenty of Fish, and Craigslist. Craigslist is a wide-open classified advertising service where employers post jobs, homeowners sell their old “Monopoly — Star Wars Version” games and unwanted gifts, and, most piquantly, people of every shape, age, color and preference seek partners for a nearly infinite variety of polymorphously perverse, chaste and romantic interactions. Craigslist is one of the top 10 visited English language sites, has versions for 450 localities in over 50 countries, and runs with only 25 employees. All of the content is written, edited (such as it is) and maintained voluntarily by users; user volunteers also provide most of the customer service through help forums.
Plenty of Fish is more specialized and not quite as successful, but perhaps more remarkable. It is a dating service localized to 50 Canadian, US and Australian cities. Markus Frind created it and devotes only about 10 hours a week to running it…and he only in the past year hired his first employee. Yet the site has 600,000 registered users (which grows rapidly despite purging 30,000 inactives a month), and receives 50,000 new photos per day. Spam-filtering of text is done by software. Filtering of photos (to make sure they are human and clothed) is done by user volunteere: in the past year the top 120 volunteers scanned over 100,000 photos each! The users provide the customer service too, through help forums.
Great business model: have the users whitewash the fence, and you work 10 hours a week for $10 million in annual profits (Stross estimates that Frind’s claim about his advertising-only profits is plausible). What are the generalizable principles. How can *I* start such a business and succeed (the road is littered with UCC-driven businesses that never turn a profit).
It is obvious that one of the most important questions is why? Why would users volunteer the time and effort to provide the content, the customer service, the photo filtering, etc.? You may think it’s obvious why users want to visit Plenty of Fish: there are a lot of lonely hearts out there. And it is 100% free to users: Frind only charges advertisers. Of course, without user effort, it won’t succeed: there will be no information about potential life partners, no help information, and lots of undesirable photos polluting the service. But no individual user needs to contribute anything: there is no requirement for volunteer hours (as there is at our local food coop), there is no public tracking of effort and peer pressure to pull your weight. It’s a free-rider’s dream.
Contributing content is easy: if you don’t submit a profile you aren’t going to get any dates. But what about photo scanning? Yes, you want to scan photos anyway: that’s why you’re there. But why not let someone else filter out the junk so you only have to filter the worthwhile photos? Is there that much of a first-mover advantage that you are willing to filter 100,000 photos per year to have a shot at being the first to contact the newest hunk? My guess is that the expected return on that investment is pretty low.
And why spend your time providing free help service to other users? Maybe Plenty of Fish is lucky to have a demographic for whom the value of time is unusually low (lonely single people with nothing else to do on Saturday night), but that just means the cost is lower to make the contribution: what is the benefit? Is it that the volunteer helpers are trying to be noticed as helpful, well-informed web geeks as a way of attracting dates?
I think the answers to these questions are transparently not obvious. If the answers were easy, we’d have a lot more people working 10 hours a week to make $10 million per year. And the answers are not likely to be something that involves only traditional economic views about incentives and motivations. Developing generalizable principles about the motivations for user-contributed content will surely need to draw on psychological explanations as well, from the psychology of personality and self, and social psychology (at least).