Here are some of my favourite Error pages, most recent first. If you're wondering what a 404 page is, it is a "Page not Found" HTTP response. If you want to try and find some 404 pages, try typing "404" or a random word in at the end of a URL.
Send mesome cool ones to be featured here, and if you are okay with it I will add credits! The cool bit about collecting them is I now have a really manual, incomplete version of theWay Back Machine
I have a bit of a backlog to add here in a folder on my desktop called "To Sort", I haven't forgotten them!
Hopefully we're not triggering too many errors and freaking out the site admins...
You can also kindly send mesomeKonami codes, I've started collecting them too and I think they're rarer!