I've been playing with XUL yesterday, and have come up with a rich client for overload feedreader, which you can check in the new snapshot I've put online [log in and choose "Rich client" in the top navigation]. In this snapshot you can now subscribe for a new user also, but still can't add a feed or import an OPML file :)

XUL enables you to create a rich client, which doesn't need to refresh it's whole window in order to do something. Of course I could have used javascript and XMLHttpRequest in my xhtml frontend, but I prefer to keep my xhtml javascript free and as clean as possible. And learning a new environment [not really a new language, except for the XML format your XUL has to be in] is quite fun ;)

Comments are welcome!