Recently I have been playing with an application called Spring. Spring is a desktop alternative for OS X. You can create canvas areas with objects that represent people, places, RSS feeds... (hooks to NetNewsWire) just about anything. The developers also have a weblog.
Andrew Orlowski of The Register...
Spring gives you a variety of panes, with object inside them that can be grouped. These can tap into the underlying infrastructure - the OS X address book, or AIM, or iTunes, or the Sherlock web services client - thanks to the much underrated power of AppleScript. It's exceedingly well done and Spring offers you a way of organizing your life, and files, as you wish.
The New York Times also has an article about Spring... Turning the Desktop Into a Meeting Place
[by way of... Jon's Radio]