I'm currently in the process of designing a 404 error page for this very website and want to be pretty original. In my research I've come across of a number of highly creative 404 error pages which are just too awesome not to share.
This is easily one of my favourites. The whole structure of the website gets pulled apart and sucked into a black hole.
Simple and effective. This 404 page uses the aliens from the retro video game Space Invaders.
I had to laugh when I laid eyes on Mail Chimps new 404 page. It's a clever homage to John Carpenter's The Thing. Somebody get me a blowtorch, it's time for the blood test!
The error page over at Disqus displays a different animated background everytime you load it. My favourite is the scene from Naked Gun.
I wouldn't even need to tell you that this is from Lego's website, it speaks for itself. Whilst I'm on the topic, when I was (much) younger I always wanted that pirate mini figure.
6) Blue Fountain Media
Blue Fountain Media has an actual fully working Pacman game on it's 404 error page. You'll be spending so much time playing on it that you'll forget the page you were trying to locate in the first place!
To me what stands out the most on Githubs 404 page is the subtle mouseover effect on the Star Wars banner.
The Blizzard website is broken. Literally.
Subtle jokes. Simple presentation. Great all around.