Every website has to perform maintenance at some point or another. Whether it's just to upgrade a portion of the site or because of some problem with the site, it's an inevitable fact of website ownership. And in many cases, maintenance requires taking your site offline for at least a few minutes. So what should you do if your site is going to be down for maintenance? You don't want users coming to a 404 or other error page. And hopefully you'd like to encourage them to come back to your si...