"So what’s Ning? Ning is an
uber-authoring tool that enables people to build these kinds of sites.
The Ning folks have built an authoring tool, and built numerous copies and variations of many of the more successful kinds of these sites. They’ve built an “Am I Hot or Not” clone, they’ve built a Craigslist clone, they’ve built a Bookshelf,
etc. They’ve captured a large part of the feature set that drives a lot
of these apps, including message boards, polls, tags, RSS and so on…
As a Ning developer, you can find a
site on Ning which is pretty close to what you’re looking for (and this
will get easier as Ning grows), and then you can clone it. After you
clone it, you get access to the source code, and you can change just
the parts you need to change to implement your own crazy idea. So,
instead of “Choose the prettiest Cat”, you make “Choose the prettiest
Llama”, or whatever. As soon as you clone the site, it immediately goes
live, and you can create a URL such as llamas.ning.com."
Lucas Gonze has created a couple of his own Ning apps already.
Update: X buys Y.