PHP 4 doesn't like to give us the name of the current class in CamelCase. Use this variable to set the correct CamelCased name of your class if you're running into problems.

Does your controller use more than one model? Your FragglesController will automatically load $this->fraggle, but if you want $this->smurf as well, try adding something like the following to your controller:

var $uses = array('Fraggle','Smurf');

Use this variable to have your controller load helpers into its views. The HTML helper is automatically loaded, but you can use this variable to specify a few others:

var $helpers = array('html','ajax','javascript');

Set this variable to the name of the layout you would like to use for this controller.

Setting this to false will stop your actions from automatically rendering.

If you'd like a bit of code run every time an action is called (and before any of that action code runs), use $beforeFilter. This functionality is really nice for access control - you can check to see a user's permissions before any action takes place. Just set this variable using an array containing the controller action(s) you'd like to run:

class ProductsController extends AppController
{
    var $beforeFilter = array('checkAccess');

    function checkAccess()
    {
        //Logic to check user identity and access would go here....
    }

    function index()
    {
        //When this action is called, checkAccess() is called first.
    }
}

Just like $helpers and $uses, this variable is used to load up components you will need:

var $components = array('acl');