server of the crowds

This post has been sitting in draft form for a couple of weeks now while I've been busy travelling the Eastern seaboard of the U.S.A.. I figure I should just go ahead an post it as is and finish up my thoughts after my trip concludes. A few months ago I made a prediction that user-created web app features would be a "next big thing" soon. I still believe this and thanks to some new popular developments I've managed to find a few better ways to explain it. You could think about it as server-side greasemonkey. Where greasemonkey allows users to add new features to a web site (and share them with other users) via client-side scripting, what I'm prediciting will allow users to do the same thing on the server side. There are advantages of this, in terms of ease of distribution/access, increased capabilities and performance. And of course users could still use greasemonkey for further features. Here's an example. Lately I've been caught up playing the Guess Where game on Flickr. Photos are uploaded to a group pool, such as Guess Where SF for San Francisco. Local residents try to guess where the photo was taken. Here's some features that would be nice to add:

• Score keeping: Who has the most correct guesses? What's the average time to achieve correct answers?
• Hide the answers for photos (so you can play even if you come late to the party)
• Add maps for located photos
• Enable/disable display of in photo notes
• When you upload a photo, input a set of hints that players can access after a certain time (if they like)

If Flickr had some sort of server-side scripting that allowed users to add these features they would probably be created within weeks. What do they gain from this? They'd gain more users who stick around longer and a more feature-rich site. They didn't have to do any market research, development or even come up with the ideas themselves. So if I'm right about this, the question arises: what's the minimum amount of functionality you need to provide to build a killer website built by the wisdom of crowds? Is it just a user login system, data storage, the serverside scripting API and perhaps a theme for general direction (for example: photos)? Maybe you don't even need the theme, just let it emerge naturally. Perhaps set up a dozen generic servers and see what happens.