These cool applications let you watch digg news stories being posted and re-dugg in real-time. They're all good at different things, and compelling for different reasons.
My favorite in terms of "hypnotic to watch" is the swarm. It's eye-candy for the ADD set.
It does have some issues as a tool, however -- if I were them, I'd have prioritized the display of the text identifying the article over the other graphics, rather than letting it mix in with the background (see above). Also, I don't entirely understand the beautiful mysterious arcs that sometimes appear, but I'm not sure I care, either.
While watching a bunch of these, the role of time gets problematic for me. I'd like to be able to replay, or step backwards (like if I missed a cool event in the swarm). And watching the big arc display for "newly submitted" in the category of science is really boring, or was on Saturday night. (See if you can even figure out how to do that that!) Finally, I would far rather go right to the article itself than click through the digg page first. That's a minor quibble, though.
There's a definite long-tail problem on digg, isn't there -- lots of the same stuff gets dugg, and it's hard to find high-quality new stuff that matches your interests.