“Where is the best place to host?” is one of the biggest questions I hear from my clients who want to build Facebook applications for their businesses. With a traditional web application, traffic buildup is gradual because you are dealing with a new audience in a nonviral channel for building hype for your website. On Facebook, however, the situation is different. With a good idea and the right viral elements in place, some applications have gone from zero page views to hundreds of millions in a matter of days. Without the proper infrastructure in place to handle this kind of traffic, your app could go down within minutes and your maximum potential for spreading the application could go out the door.

There are two hosting services at the time of this writing that I suggest you look into. I won’t go into detail, but these services provide a means of quick scaling as traffic to your application increases. The first—and my preference—is Amazon EC2 (Elastic Compute Cloud) combined with S3 (Simple Storage Service) for backups. EC2 gives you a very fast way to programmatically scale your app as needed, while requiring you to pay only for the bandwidth and servers you need. The second service is Joyent. Joyent provides speedy scaling to new servers as needed, and it provides a direct line to Facebook so that your applications will have the fastest connection possible to Facebook’s servers. Beyond those two suggestions, of course, you can always find a good hosting center if you know what you’re doing and negotiate your prices as you need to scale. Just be prepared to have some servers of your own ready as a backup!

Once you have selected your service, what’s the best way to set up your servers to prepare for an influx of traffic such as I mentioned? That would take an entire book to detail, but my best suggestion is to keep your data as persistent as possible, so that if you need to fire up another instance of your server, it can automatically know where to retrieve the data. I strongly recommend hiring a good system administrator if this is not something you think you can handle, and at least have him on hand to prepare for the event of heavy traffic.