For the past month or so, I've been one of a handful of people testing out some new software that Dave Winer cooked up. It's called FlickrFan it's now available for anyone who wants to try it out.
It connects your flickr account to your desktop, backs up your flickr photos, and connects them to your screensaver.
The thing I use most is to power a screensaver on our big flat panel HDTV screen with the flickr photostreams of my friends and loved ones. If you have a flickr account and a mac, give it a try.