MeatballWiki is a very interesting wiki which discusses online communities with a strong focus on wikis. It’s been around for ages, but now they have hacked some neat AJAX functionality into the site (via Ajaxian). RecentChanges fetches new changes from the server in regular intervals and allows you to filter the view using Meatball’s unique concept of EditCategories without reloading the page. Page histories use a split pane model where diffs are fetched from the server without reloading the page. I’m missing an obvious way to bookmark diffs, though. As for Recent Changes, the coolest thing are real-time changes. Wikipedia used to have them on the web, but the script wasn’t built to scale. You can still get them via IRC on irc.wikimedia.org, though, and there’s cool tools like CryptoDerk’s VandalFighter which make use of that.