Brandon Savage has a few recommendations when it comes to taking your application to the next level - scaling it up to meet the needs of the masses using your application every day.
The modern age has brought us lots of new ways to take a growing site and scale it. From Amazon Web Services to cloud computing and grid computing, to Mosso and Akamai, there are lots of options we should consider. This article won't make a recommendation as to which you should pick; it will simply discuss what each service has to offer and leave it up to you.
He suggests four different alternatives to pick from when making the move up - the old standby of purchasing more hardware, making use of the Amazone Web Services, using a "cloud" like Mosso or implementing a Content Delivery Network to lighten the load and spread it out across a wider range of servers.