Twitter users are very well aware of Fail Whale image that pops up whenever twitter is down due to some reason. Twitter’s fail whale also has fan site – http://failwhale.com/
Google Wave has its own similar feature which is shown when Wave is down for maintenance.
It seems that Google Wave’s maintenance page can be still seen when the service is up and running:
For those who know jQuery, try to see the source code of the above Google Wave failwhale page. They have used jQuery for animating the clouds and waves.