Since I've received several messages on this, I figured it was best just to post a blog...
Apparently the server was down for several hours. Since I've been busy all day, I hadn't yet visited any of the websites, so I didn't notice. When I received an email inquiring on the inability to access the server, I checked it out and found the issue - which was nothing a reboot couldn't solve.
The server logs had nothing out of the ordinary for any of the websites, so there didn't appear to be a major attack launched. I don't know of any on-going maintenance in the datacenter, so it probably wasn't anything there. It just seems like the server had a random crash. Yay, computers!
Feel free to email, call, or text, me anytime something like this happens in the future.