I am sure everyone has seen this but still hilarious

Tin Foil Hat
http://www.worldofwarcraft.com/info/items/tinfoilhat.xml

Found a whole bunch of April fools links on Neowin
http://neowin.net/index.php?act=view&id=39173

My favorite was the Black Temple Attunement Chart where just ONE of the steps required that EVERY boss of EVERY instance in Outland be killed WITHIN 10 MINUTES OF EACH OTHER ON HEROIC MODE, lol, and some people actually BELIEVED it. Jeez.

Probably the best one that Blizzard did was before the game was released, there was very little information about what all the classes/races were going to be and then on April 1st, they posted a playable 2-headed ogre that you could play... but you could only control one of the heads and another player controlled the other.

I still am amused by the outrage caused by the BC "Pandarian" race.