New MinneDemo site
As an organizer, using a wiki has some great strengths: anyone can easily add their name or sign up to present, add photos or links, and so on. But it has some downsides as well, namely that organizers can't get attendee's contact info unless they leave it on the site (which many people are loath to do with their email addresses). This is especially bad for MinneDemo, where we need to be able to contact presenters.
The final blow against PBWiki for us was that in the lead up to next month's MinneDemo, the barcamp.org site has been extremely flakey. Almost every edit to the page resulted in a 500 error. This continued to happen for weeks at a time. Finally, Dan Grigsby and I decided that enough was enough and wrote a simple sign up form in Rails.
Not only is the new site more reliable, but we were able to tailor it for our needs. We now collect email addresses for attendees and presenters, and I'm adding niceties every day, like an RSS feed of attendees.
We'll still use barcamp.org to promote our events, but our new site will continue to evolve. I hope to develop it into a full-fledged un-conference planning tool.