I really like its emphasis on cloning others' projects and then tweaking them to suit your own needs. It really reminds me of the old days of the Web, when you'd see something cool, View Source on the page to get how it was accomplished, paste it into your own page, and tweak it to your heart's content. That's how everyone learned to do everything, and it made for a fast revolution.
As all the cool stuff has migrated to the back-end, the View Source method has become less and less useful. This brings that all back -- I hope.
Ning is a free online service (or, as we like to call it, a Playground) for people to build and run social applications. Social "apps" are web applications that enable anyone to match, transact, and communicate with other people.Link (via Waxy!)
Our goal with Ning is to see what happens when you open things up and make it easy to create, share, and discover new social apps. These might include for any city, your own take on Craigslist...for any passion, your own take on Match.com...for any interest, your own take on Zagat...for any event, your own take on Flickr...for any school, your own take on the Facebook...for any topic, your own take on del.icio.us...for any mammal, your own take on Hot or Not or Kitten War.
You choose the app, decide for whom it's most relevant, create the categories, define the features, choose the language - or just clone an app that's already up and running on Ning - and be on your way.