When deciding on a host, consider: Why do you need hosting? How much experience do you have deploying Rails apps? And how much traffic do you expect?
First, if you're just playing around or don't expect to be deploying anything huge, go with a free trial at DreamHost. Just configure your domain in their panel to be a Rails app, upload your project folder so the "public" directory matches the DocumentRoot you selected, and you're good to go.
Second, even if you have tons of experience building server environments and dancing around a unix shell, all of these hosts for smaller apps allow SSH access so you can set things up exactly how you like it.
Third, if you're expecting more than 1k dynamic hits a day or so, you'll want to deploy on a VPS or a cloud platform. Otherwise, if your app spits out pages that can be completely cached, a cheaper shared host will get the job done.Read more »