I'm using EngineYard Solo which is a great deal ($25 minimum) and perfect to get up and running quickly. They're also working on tools to help scale application

I'm using EngineYard Solo which is a great deal ($25 minimum) and perfect to get up and running quickly. They're also working on tools to help scale applications across multiple instances. I couldn't recommend Solo enough if you're just getting started, it makes working with EC2 a piece of cake.