Though we seem to be through the worst of Diablo III's humiliating server outages at launch this week, who knows when those things will need to be worked on again. Logging in to Battle.net and waiting for the credential verification to time out is a long and stupid way of being told you can't play the game.
To that end, someone's drawn up a free app for Android smartphones that gives the status of the servers. Eluamous, the developer behind it, also wrote apps checking the server status of World of Warcraft and Star Wars: The Old Republic. This monitors the status of all Diablo III servers in North America, Asia, and Europe.