The site looks great. I assume you are working on this - but do you have screen shots of your admin interface or a list of available images? (You are probably well aware of this, but creating EC2-Windows images on a micro instance is ridiculously painful).

Not sure what you could do with AppHarbor that you couldn't do with this. You could set up a build server image that pulls from a Git or Hg repo, and repoints IIS...