From what I’ve seen so far, Ning looks like an awesome web application. It’s billed as a tool for building social networking sites. For people to make sites they need to sign up with the developer beta program. I signed up and am waiting until they have room for me.
I can see quite a bit of variety, and every site seems responsive. But I don’t yet know that it can easily be used to build a site like craigslist. Time will tell.
One page of particular interest is the confess page. The page uses AJAX (I finally decided to give up the terminology war). I guess I am a sucker for visual effects, but there is an animated gif spinner logo, like the one in Firefox and Mac OS X, that spins when the AJAX request is being loaded, right next to where the user clicked. Very cool.
Update: (9:08pm) Just got word that I am now in the developer program. More informed opinon coming shortly.