This is probably old news to you, and I've read about Digg's problems in the tech media, but I just realized
how much reddit has eclipsed Digg in referral traffic.
I've always gotten way more attention from reddit (some science bloggers have told me that reddit readers are a "smarter set"), but when I did get Digg bumps they were often of greater magnitude. No more. Not only are referrals from Digg much more rare than they used to be, but they aren't as significant as reddit. So of course I checked out Google Trends:
Even StumbleUpon has now surpassed Digg in search queries. Was Digg the MySpace to reddit's Facebook? And of course Slashdot keeps going.... (Slashdot is so well established that I doubt many people are "searching" for it, so these trends probably underestimate its reach and influence).