XMod is as close as you can get without building it yourself as far as I know.  There are some others, but they all do relatively the same thing.

What you are describing sounds kind of MS Access though.  It has some nice templates that you can even convert to a web project.

It sounds like you are familiar with Databases, so another option might be something like Iron Speed.

we are currently developing a module, that has many of the features you are asking for:

• creating custom tables
• accessing existing SQL tables from any SQL database
• visual designer for forms and views
• moderation and notification
• hierarchical forms (1:n)

have a look at the description here, you can also try it yourself in our playgroud here (see login info at the bottom of the page).