fastest public web app framework for quick DB apps?

Question

I'd like to pick up a new tech for my toolbox - something for rapid prototyping of web apps. Brief requirements:

• public access (not hosted on my machine) - like Google's appengine, etc
• no tricky configuration necessary to build a simple web app host
• DB access (small storage provided) including some kind of SQLish query language
• easy front end HTML templating
• ability to access as a JSON service
• C# or Java,PHP or Python - or a fun new language to learn is OK
• free!

An example app, very simple: render an AJAXy editable (add/delete/edit/drag) list of rich-data list items via some template language, so I can quickly mock up a UI for a client. ie. I can do most of the work client-side, but need convenient back end to handle the permanent storage. (In fact I suppose it doesn't even need HTML templating if I can directly access a DB via AJAX calls.)

I realize this is a bit vague but am wondering if anyone has recommendations. A Rails host might be best for this (but probably not free) or maybe App Engine, or some other choice I'm not aware of? I've been doing everything with heavyweight servers (ASP.NET etc) for so long that I'm just not up on the latest...

Thanks - I'll follow up on comments if this isn't clear enough :)

Answer 1

C# or Java,PHP or Python - or a fun new language to learn is OK

How 'bout Javascript? This place hosts server-side Javascript ticking most of your other boxes. So you can use the same language for client- and server-side stuff (which I find very handy). [Caveat: I only played with their service; seemed cool though. I use Javascript on the server-side on IIS and on Tomcat (via Rhino).]

Answer 2

For something bleeding edge - A new version of spring roo was released recently. With it you can create a great web app in 10 minutes. Supports GAE and GWT...

http://www.springsource.org/roo