These folks are still in Beta, but early on I was using their platform and was able to quickly build and deploy rich Internet apps. Downside, you need to use their programming tools and languages but the upside is that it is an MVC framework so it is easy to iterate and change as you build.
Poll of the Week
Could your inbox use a little more awesome?
Sign up to get a daily dose of awesome gov-focused resources, trainings, blogs and articles to help you do you job better.