Admin Module with highly customized UI I have a web app with a complex database that I created for a previous project. I'd like to integrate that old project into my new drupal site. I don't need it to be fully drupal-ized, but I need to at least leverage drupal's user authentication.

I'm trying to find a good tutorial about creating a module which provides an admin page and has a very customized UI. I don't need drupal to create form items for me. Any suggestions?

My UI fetches and updates all of its info via AJAX, so I need each of those AJAX calls to be at least minimally managed by drupal for user authentication purposes.

Does that make sense? Any suggestions?
Have a look at hook_menu(). It's the cornerstone to define pathes and who has access to them.

In drupal you define a path by implementing hook_menu in a custom module. There you define what php functions are called and what user roles do have access to it. This way you can route your AJAX calls through drupal autentication and authorisation.