While I love
Electric Sheep as a screensaver, it sucks power and rarely updates because I don't idle my laptop all that much.
OS X comes with a built in RSS Photo screensaver that I have always wanted to use in combination with
Flickr Interestingness, but Flickr does not supply an RSS feed for that particular part of flickr, and the
ad hoc third party options only scraped the preview photos which don't look all that interesting when blown up to full screen resolution.
Enter Yahoo! Pipes, in all it's deliciousness.
Some hero put together
a pipe that harvests larger versions of the photos, and produces an RSS feed.
Awesome.