Browser based WebDAV client?

There's a plugin for Firefox which handles WebDAV.

Webfolders is a firefox extension that gives you the ability to view the contents of WebDAV servers in the browser and use the full functionality of the WebDAV protocol.

Look at the AjaxFileBrowser from ITHit. Pretty slick, and has FireFox & Chrome PUT support for uploading. IE, drag-and-drop from your desktop to the browser. They have a fully functional demo site up at http://www.ajaxbrowser.com.