I propose April 4th as the world's first international computer holiday. After all, 404 combines the Homer Simpson, “Doh!” of hitting a dead link with the April Fools, “Gotcha!” deserved for complacently believing anything posted.

I further like the idea of honoring 404 as it’s probably the most common error transmitted over the internet:
"HTTP Error 404 The page you are looking for might have been removed, had its name changed, become temporarily unavailable, or never existed. (Check you're lousy typing.)"

On 404 Day we can celebrate the painful comedy of great failed attempts, inspirations that lead nowhere, webpages with dead links the moment they're posted, and search engine listings of long gone URLs. (Oh, and sloppy typing.)

On April 4th we can reavow our faith that the truth really might be out there, if only one can find the right search words.

On 4 of 04 we renew our positivism, knowing that when we come to a web dead-end, we never give up, never surrender. Rather, we back up and click again.

On Four-the-Fourth we rededicate ourselves to follow that Star-dot-Star *.* like Don Quixote, until reaching our quest (or the end of the Internet--whichever comes first).

On 4-0-4 we laugh at ourselves for getting angry over the Bluescreen-of-Death, the Illegal Operation, the Fatal Error and/or System Fault the machine commits when we aren't even touching it! Deus ex machina!

On IV-IV we find understanding (unlike the joke of Microsoft error message numbers).

On 404 Day we forgive all the crap that computers, spammers, pop-up advertisers, virus spreaders, crapware coders, etc. etc. etc. put us thru.
(But on April 5 we remind ourselves to get even with whomever, whenever possible!!!)

On the fourth day of the fourth month of any year which can be represented digitally, we recall that an infinitude of monkeys keying infinite wordprocessors over endless time will recreate The Hitchhiker's Guide to the Galaxy--but it's still plagiarism! So despite the magnitude of such efforts, over-engineering is over-engineering and GIGO is GIGO is Garbage in / Garbage Out.
[No offense meant to Douglas Adams's literary monkey biz. Hitchhiker's Guide to the Galaxy]

In cyberspace we trust. In webmasters and ISPs we must hope.

Since every obsession thrives on the web, 404 already has a webring, as well as 404 page collectors. Consider URLs such as www.mindspring.com/~isixtyfive/404page/404_main_list.html which, since beginning this article has gone…. wait for it…. 404! How sweet is that?!?!?! Doesn’t that perfectly reflect the April Foolish quality of my proposed fest-day?

Sadly, like too many other pseudo-holidays, April 4th will be a workday unless it falls on a weekend in which case it would remain a workday to weekend workers most of whom aren't computer nerds, anyway. Oh well…

Lastly, I propose Thomas Edison be the date's patron. This noted American electronic tinkerer avowed:
          "I have not failed 700 times. I have not failed once. I have succeeded in
           proving that those 700 ways will not work. When I have eliminated the
           ways that will not work, I will find the way that will work."

Excelsior and 404, dude! That's it exactly! Not to mention once Edison found the way that worked perfectly, he de-engineered a shorter lifed version so he could sell lightbulb upgrades. Classic 404 tomfoolery.

By the way, 404 manifests off-line, as well.

On telephone systems it's: "The number you have reached is no longer in service and there is no new number. Please check the number 411 gave you and dial again."

“Doh!”

And then there's the ultimate 404 tragicomedy, the US Post Office:
“Not at this address.” [Yes I am!]
“Moved, left no forwarding address.” [No I didn't!]
“Address forwarding expired...” [I did not move!]
“Delivered to wrong address.” [404.]

“Gotcha!”

Happy 404 everyone!

*IMHO = In Monkey's preHensile Opinion