I found this DNN site by helping out one of the users here in the forums.  This guy (I'm assuming) has taken DotNetNuke to nearly insain levels using all of the benifits that come from using DNN.  And it looks like he's keeping it all free in the spirit of DNN.  It's really pushing the limits of your code as would make a great showcase site for what people can do with a pretty much default install of DotNetNuke and some nice skins.

He's having some growing pains at about 4 million hits a month across 2000 user created portals but from the user experience side you wouldn't know.  The site is;

http://www.wowguilds.com