Last week, there was a thread on the European forums about what really happened during the weekly downtime. Sure, some people said the boring answers of various things having to do with software and hardware. Others were more of the fanciful variety involving the hamsters that run the servers being fed. However, I like the more RP approach to the situation.
Goblins and gnomes are using refitted shredders to sweep the streets and repaint the buildings. Mankrik's wife has stopped playing dead for a little while and is grabbing a bite to eat with her husband. The stormforged dwarves are hard at work forging more drops for the raids that have reset. The streets of Orgrimmar are empty with tumbleweeds blowing down the streets and an old orc in a rocking chair is playing the theme to The Good, the Bad, and the Ugly on an old harmonica (the music was in the tumbleweed's contract).
What do you think the World of Warcraft does while we're temporarily forced offline?