Here's a link to a nice article where the author at boxesandarrows.com discusses the principles of task flow in web applications. His approach makes for some nice, if not overly simplified, web pages. Generally speaking, I agree that his approach is good for the majority of web users.
xplanner.org offers a "project planning and tracking tool for eXtreme Programming (XP) teams". So far, it's looking pretty cool, and useful. The organization and usability seems to be right up our alley.