This morning, at around 06:30 server time, the website stopped responding. The cause of this downtime was a hardware glitch which made the web server machine unresponsive. It's difficult to identify exactly what this glitch was, but logs indicate evidence of memory corruption.
All services are back up and running (obviously, since you are reading this), but the glitch is a pretty strong indication that it's time to sunset the server (fungus). It's a machine purchased May 2012, so it's been doing well up until now.
I will be looking to migrate the web server to new hardware once I have a chunk of time to do it. There will likely be some more extended downtime while this migration is taking place, but there will be a proper heads-up for it before hand.
Either way, I apologize for any inconvenience caused by this downtime.