In the early days of the web, scheduled maintenance could be done from time to time, and servers just taken offline for several hours.  However, those days are long gone – at least I thought so, until I came across this from the IRS tonight (8pm EST):

Unfortunately, I can’t pay my taxes to anyone else.  So let’s see, I can post a cat video on Facebook 24x7x365, but pay my taxes…ehh..