Reddit is down. Not the site itself (as far as I know) but their DNS servers, which are hosted at name-services.com. That site is now full of adwords spam. It's probably been hacked, and any site that used them for DNS service is effectively off the air.
It's odd how addicted to Reddit I have apparently become. I keep hitting reload in the vain hope that the problem will fix itself even though I know it will almost certainly be hours or days. Ironically, reddit itself is almost certainly still up, but there's no way to get to it without knowing its IP address, and the only way to find that out (unless you happen to have a cached copy or wrote it down on a post-it) is, in reddit's case, to get it from name-services.com.
I should look into getting some backup name servers for my own domains. But I probably won't.
UPDATE: Shimon Rura points out that every cloud has a silver lining.