Okay, so, I'm reporting this a bit late, but I think
xkcd got the cake for best AFD ever.
First, I got there, and there was a normal comic, with a weird quote on the page, so I figured the quote was the AFD. I continued to believe that until today, when I was talking to someone about the comic, and they told me a completely different comic. So, I started digging around their forums.
Apparently, there's Javascript in place that checks several things about your computer, like browser, OS, domain and location, and gives you different comics based on the result. Added to that, the comic changes length according to your window size.
I'm reading up on the different versions on their forums, and it seems there are over 15 variants :O
The comics are still up, by the way