I've heard about web frameworks like Rails, Django, CakePHP and others, that help programmers to quickly create dynamic websites which are basically a web GUI to interact with a database.
I was wondering if there are ways to "generate" these Admin Panel GUIs pretty much automatically, something like a Microsoft Access for the web? Where the "database" can be designed by non-programmers, and the resulting web app to work with that data be generated automatically?
I suggest you to go for RubyOnRails, it's just perfect for this purpose.
You just have to spend your time learning ruby and rails (in stackoverflow you can find a lot of suggestion about "how to start")
After that these are the key elements you need:
ActiveResource - is a library that allow you creates a persistable domain model from business objects and database tables, where logic and data are presented as a unified package. Zero configuration...
Scaffold or NiftyScaffold - A Rails Scaffold is an autogenerated framework for manipulating a model.
If u need a better interface have a look at the web-app-theme generator
I don't add others word, check this framework and have a look at some RailsCasts in order to understand the power of ROR.