Animating the opacity of certain page elements
You have written a simple plugin as it is (see:http://learn.jquery.com/plugins/basic-plugin-creation/).

Firstly I don't think I'd put the document ready stuff inside the plugin. Secondly you should remember that jQuery objects are always based on an array (non matched selectors being a zero length array), so you can always use and return the .each function. As a caveat to that, if you are performing the same task on all elements in the jQuery object (and there isn't data bound to them or any calculations that you need to do on a per object basis) you do not need to use .each.

(function( $ ) {

    $.fn.animateFadin= function(amount) {

        return this.each(function() {
             //this is now an individual element you can manipulate
             this.delay(amount).animate({
                 opacity: 1
                 }, 700);
        });

    };

}( jQuery ));


Or in the simple case:

(function( $ ) {

    $.fn.animateFadin= function(amount) {

        return this.delay(amount).animate({
                 opacity: 1
                 }, 700);
    };

}( jQuery ));


You can now call $('#zone-menu-wrapper').animateFadin(500); 

If you understand this then you should be able to use the `.each variant to achieve the delays in a marginally more tidy fashion.  What you might want to think about adding though is a callback to the animate function if what you hope to achieve is one element animating after the other.

To do that you would not use each but a simple recursion. Pseudo-code without error/bounds checking:

function chain(this, them) {
    If (!this) return;

    nextThis = them.pop();

    this.delay(whatever).animate({...}, 100, function() {
            chain(nextThis, them);
    });
}


Call this from within the body of animateFadin with the head and [rest] of the jQuery object's object array. What would be nice is to write a plugin to which you pass a function (the action, in your case delay then animate) so that this is reusable behavior. Maybe it already exists?

All code untested and written on my phone, which was harder than I thought! Good luck.