AppHarbor is awesome. The development process could not be any easier. You literally just create an MVC project and push it to your AppHarbor git repo and you're done. They also have support for SSL, multiple collaborators, and error logging. There are also a few features that I know are coming that will make it all the more awesome.

The add-on program seems pretty cool too. We're planning on adding EffectCheck to the list of supported APIs soon.